ALLERGOL. ET IMMUNOPATHOL., 1998;26(4):171-194
POSITION PAPER
Adverse reactions to cow''s milk proteins(*)
M. Martín Esteban*, J. Bone Calvo**, A. Martorell Aragonés***, S. Nevot Falcó****, and A. M.ª Plaza Martín*****
*Allergy Service. Hospital Infantil "La Paz". Madrid. **Allergy Section. Hospital Infantil "Miguel Servet". Zaragoza. ***Allergy Section, Pediatrics Service. Hospital General Universitario. Valencia. ****Allergy Section, Pediatrics Service. Hospital General de Manresa. Manresa (Barcelona). *****Allergy and Clinical Immunology Section. Hospital Clinic-Hospital "San Juan de Dios". Esplugues (Barcelona).
Working Group on Allergy to Cow''s Milk Proteins, from the Spanish Society for Pediatric Clinical Immunology and Allergy.
INTRODUCTION
Cow''s milk, or a formula derived from it, is usually the first non-homologous food that humans receive in large quantities. This means that it is also the first food antigen that humans encounter. It is therefore no surprise that cow''s milk produces more adverse reactions in early infancy than any other food.
The classification of adverse reactions to foods proposed by the EAACI (1) distinguishes pathogenically between two large groups of adverse reactions to cow''s milk proteins (CMP) (table I): CMP allergy and CMP intolerance. This paper will not consider situations of intolerance to other cow''s milk products (e.g., intolerance to lactose) or allergic reactions to added products (penicillin, peanut proteins or other proteins transmitted via the fats that the formulas contain).
1. CMP allergy (hypersensitivity): adverse reactions to CMP, with a proven immunological mechanism. They include both IgE-mediated immunological reactions (immediate hypersensitivity or allergy), and those produced by any other known immunological mechanism (reactions not mediated by IgE). The former are characterized by the presence of high titers of IgE antibodies to cow''s milk, and the latter by an increase in specific antibodies belonging to other classes of immunoglobulins, immune complexes, or cell-mediated immunity responses.
Table I | ||
Adverse reactions to cow''s milk proteins | ||
| Allergic reactions | ||
| (demonstrated immunological pathogeny): | ||
| a) Immediate (IgE mechanism): | ||
| Immediate allergy or hypersensitivity to CMP. | ||
| b) Via another immunological mechanism. | ||
| Intolerant reactions | ||
| (non-immunological or unidentified pathogeny): | ||
| CMP-sensitive enteropathy. | ||
| Eosinophilic colitis. | ||
| Other possible intolerances (in which the involvement of CMP etiology is doubtful): | ||
| Idiopathic pulmonary hemosiderosis. | ||
| Infant colic. | ||
| Ferropenic anemia. | ||
(*) The recommendations in this statement do not indicate an exclusive course of medical case. Variations, taking in account indiviudal circumstances, may be appropriate.
In addition to evidence of a relationship between the intake of a foodstuff and the appearance of symptoms, these altered immunological parameters must also be directly involved in the pathophysiology responsible for the symptoms. For this reason, although all known immunological mechanisms may be involved in the CMP allergy, only IgE-mediated immediate hypersensitivity reactions present characteristics that permit identification: typical symptomatology which is easy to recognize and test, and reliable, reproducible diagnostic methods. The involvement of other immunological mechanisms is also likely, but the evidence is as yet inconclusive.
2. CMP Intolerance: adverse reactions to CMP in which no immunological cause has been identified. Because of the absence of a known cause and the variability of the morphological lesions, when present, these situations are grouped together as a common syndrome, characterized by diverse gastrointestinal symptoms with variable repercussions on the nutritional state of the patient. Symptoms improve when CMP is removed from the diet, and reappear after reexposure.
In some of these situations (such as CMP-sensitive enteropathy, eosinophilic colitis) an immunological cause is suspected but not proven; it there-fore seems advisable to maintain the common term "CMP intolerance".
The distinction between IgE-mediated immediate CMP allergy and these latter processes is important not only from the conceptual point of view. The pathogenic differences form the basis of the symptomatology and evolution of each condition and the possibility of deploying different preventive and therapeutic measures in each case.
Finally, there are other processes which do not have a well-defined pathogeny and whose etiological relation with cow''s milk is doubtful or inconsistent (e.g., they do not always remit with diets lacking CMP, nor are relapses always observed after reexposure). These include idiopathic pulmonary hemosiderosis, colic, and certain forms of ferropenic anemia.
IMMEDIATE COW MILK''S PROTEIN ALLERGY
Epidemiological data
It is difficult to evaluate the incidence and prevalence of CMP allergy on the basis of results of epidemiological studies published to date, due to inconsistencies in study design (e.g., indistinct inclusion of patients with CMP allergy and CMP intolerance) or the application of imprecise diagnostic criteria.
A recent review (2) of prospective studies performed worldwide observed an incidence of adverse reactions to CMP (allergy and/or intolerance) in between 0.3 and 7.5% of the population during the first year of life. In series in Spain CMP allergy is the third most frequent cause of food allergy (24.5% of children with food allergy), after eggs (34.4%) and fish (30.4%) (3).
Factors that condition and favor sensitization
The development of sensitization and food allergy depends on the interaction between the genetic predisposition of the individual and factors in the environment, especially regarding exposure to food proteins. There is a delicate balance between tolerance and sensitization, which depends on a range of factors (table II):
Table II | |
Factors that condition and favor sensitization | |
| Factors dependent on the individual: | |
| Genetic predisposition. | |
| Factors dependent on the antigen: | |
| Nature of the antigen. | |
| Dose of the antigen. | |
| Factors dependent on antigen-individual interaction: | |
| Exposure of mother during pregnancy. | |
| Transmission of antigens through the mother''s milk. | |
| Frequency of administration. | |
Genetic predisposition
It is well known that both the capacity to syn- thesize elevated levels of total IgE and the capacity to trigger IgE-specific responses have a genetic basis (4). The production of small quantities of IgE against food seems to be a normal phenomenon in infants (5), but those that present a genetic predisposition towards allergy (individuals with "atopic risk") tend to produce IgE against food during a prolonged period of time, even in the absence of symptoms (6).
Between 41% and 73% of children with CMP allergy present a family history of atopy (7); in one group of infants at high risk for atopic disease evaluated on the basis of family history, followed
up prospectively from birth, 3% developed CMP allergy (8).
Nature of the antigen
Cow''s milk contains more than 25 proteins that can act as antigens in humans. The principal or major allergens are ß-lactoglobulin (to which 60-80% of patients react), caseins (60%), *-lactalbumin (50%), and seroalbumin (50%) (9, 10). There may be differences according to study population, and in most cases more than one allergen is involved (10). It has been hypothesized that new allergens may be formed during the enzymatic digestion of the proteins, but there is not sufficient evidence for this theory (9). It appears that the antigenic determinants of ß-lactoglobulin and casein are more structural than conformational (11, 12), which may account for their resistance to heat.
RAST and RAST inhibition have shown a cross reaction between cow''s milk and goat''s and sheep''s milk (13), due to the similarity of their proteins. Most individuals who are allergic to CMP do not tolerate the milk of these other species (14).
Sensitization to bovine seroalbumin may be responsible for the allergy to beef that is sometimes observed in these patients. However, this protein is thermolabile and is denatured during cooking. Using a double blind food challenge, Werfel et al. found a reaction to beef in only 10% of those allergic to CMP (15).
Heat treatment only partially reduces CMP allergenicity. Low temperature pasteurization (75° C for 15 seconds) ensures bacteriological quality, but does not significantly reduce antigenicity or allergenicity (16). High temperature treatment (121° C for 20 minutes) destroys the allergenicity of whey proteins, but only reduces the allergenicity of caseins (2).
Dosage of the antigen
Experimental studies indicate that the type of immunological response may be modulated by the dosage of the antigen administered orally. Very small doses are particularly sensitizing (17, 18); quantities of nanograms or picograms of ß-lactoglobulin induce hypersensitivity, while this same antigen at doses of milligrams induces tolerance (19). This may be the case when food antigens are transferred via the placenta or the mother''s milk.
Exposure of the mother during pregnancy
There are reports of possible passage of food allergens from the mother to the fetus via the placenta and the intrauterine production of CMP-sensitive IgE antibodies (20, 21). Other studies conducted in newborns at high risks for allergy have not shown IgE specific to food, despite using highly sensitive techniques (22). However, it has been observed that the T cells of newborns can be primed "in utero", since they are able to respond to food allergens (23) and inhalants (24).
In some patients sensitization may begin "in utero", but without clinical manifestations. Sensitization may evolve subsequently after birth, with larger doses of the antigen administered either sporadically or separated by long intervals (i.e., weeks or months).
Transmission of antigens via mother''s milk
It appears that the excretion of food antigens via mother''s milk is a general phenomenon (25). ß-lactoglobulin is detected in the milk of 95% of lactating women, with a mean concentration of 4.2 micrograms/liter (range 0.9-150 micrograms/liter (26). There is as much ß-lactoglobulin in a drop of cow''s milk as in 200 liters of mother''s milk. Even so, each drop of mother''s milk contains approximately as much ß-lactoglobulin as the quantity of pollen allergen inhaled daily during the pollen season (27).
The immunological significance of this transmission of food antigens during breast-feeding is not clear, but it may be a means by which the infant at high risk for atopy becomes sensitized. This may explain why a considerable percentage of infants with CMP allergy begin to show symptoms in response to their first bottle of formula, after exclusive breast-feeding. In addition, children with immediate CMP allergy do not usually present a history of artificial feeding since birth. In a series of 127 patients with IgE-mediated immediate CMP allergy (28), only one had been fed artificially since birth. In 64, all of whom had been breast-fed, the symptoms appeared during the first day of artificial feeding: 34 had been bottle-fed in the maternity ward and the other 30 had had no apparent contact with CMP. Ghisolfi et al., in a more recent study (29), reported that of 125 infants with IgE-mediated immediate CMP allergy, 121 (97%) had been breast-fed; in contrast, only 33 of the 92 with CMP-sensitive enteropathy or colitis had received mother''s milk (38%, a percentage similar to the figure for breast-feeding in the general population in the area of study). These data suggest that artificial feeding from birth with adapted formula does not seem to favor the development of IgE-mediated immediate CMP allergy in the infant. It may be that uninterrupted feeding with large quantities of milk from the neonatal period onwards facilitates tolerance (19).
Frequency of administration
With equal doses, continued administration of the nutrient can favor tolerance, whereas intermittent administration can increase the risk of allergic sensitization (19). For this reason, isolated bottle-feeding at unusual hours can favor sensitization to CMP. This may occur in newborns at risk for atopy, if given a bottle of cow''s milk or adapted formula before beginning breast-feeding, which is then continued exclusively during the following weeks or months (28, 30).
CLINICAL ASPECTS
The main characteristic of immediate hypersensitivity to CMP is the presence of CMP-specific IgE antibodies. However, their detection and quantity do not always parallel the clinical manifestations that can follow CMP intake.
A range of factors modulate clinical response in immediate food allergy (31): some are allergen-dependent, such as the quantity of the sensitizing food consumed. Others are individual-dependent, such as the intensity of the sensitization, reflected in the rate of specific IgE antibodies, the capacity of the cells involved in the allergic inflammatory response to release mediators, and the sensitivity of the target organs to the mediators released.
As a result of the interaction of these factors, a range of clinical-immunological situations is found, from immediate hypersensitivity to CMP with-out demonstrable related symptoms (usually detected in older children who are generally polysensitized) to immediate hypersensitivity with general symptoms that can affect different organs. In the middle of the range are forms with localized symptoms limited to the target organ (the digestive tract), such as acute vomiting and diarrhea.
In the most common form of presentation, in which manifestations are general, symptoms may even begin during the period of exclusive breast-
feeding. In these cases, reactions to the CMPs in the mother''s milk usually occur several hours after maternal intake. The symptomatology is similar to that found in other children with CMP allergy, although atopical dermatitis appears to be the predominant symptom (2).
In most cases, symptoms appear at the beginning of artificial feeding, in general after a period of exclusive breast-feeding. Symptoms tend to begin shortly after the beginning of artificial feeding. They may occur immediately after the first apparent intake of cow''s milk (2, 30). In a series of 52 cases published in Spain (30), symptoms began within a week of starting artificial feeding in 77%.
This short interval between the beginning of artificial feeding and the onset of symptoms means that the age of appearance of clinical manifestations is related to the age when artificial feeding in started. Maximum incidence is between 3 and 4 months of age (30). In most cases, symptoms appear during the first year of life, and onset after the age of 2 years is rare (3).
Symptoms usually appear a few minutes after intake of CMP (immediate reaction), almost always within an hour. It is unlikely that reactions that appear several hours or even days after CMP intake (delayed reaction) are due to IgE-mediated hypersensitivity.
Some authors classify responses as immediate or delayed (32) or even immediate, intermediate and delayed on the basis of the time elapsed between CMP intake and reaction (33). Habitually, in patients with immediate onset the presence of IgE antibodies is demonstrated, whereas in the other groups, those which mainly include reactions defined as CMP intolerance (34), these antibodies are not usually found. Here, the age of the patient at the time of diagnosis is important, since some very young infants may present immediate reactions to the challenge without evidence of IgE specific antibodies, which may subsequently be detected in a later examination (35).
Clinical manifestations
Most children (75-92%) with CMP allergy present more than one symptom (2). Acute dermatological manifestations (erythema, urticaria, angioedema) constitute the most frequent clinical symptomatology, appearing in between 60% (2) and 80% (30) of patients, in clear relation to CMP intake. They may be the only sign, or may accompany other non-cutaneous symptoms. Episodes of urticaria and/or angioedema are of variable intensity and distribution; the erythemas are of variable morphology and localization, often appearing on the cheek or on sites of contact.
CMP allergy is frequently accompanied by atopic dermatitis. In 470 patients with atopic dermatitis and proven food allergy, Sampson found positive CMP challenge or "convincing" history in 38% (36). Host and Halken observed atopic dermatitis in 56% of their patients with CMP allergy (35), although they did not indicate whether the dermatitis was confirmed in the provocation test. Given the pathogenic and clinical characteristics of atopic dermatitis the result of non classical hypersensitivity compatible with the final stage of a late cutaneous reaction, with predominant activation of Th2 lym- phocytes by the IgE-carrying Langerhans cells (36) a controlled food challenge must be performed to confirm that cow''s milk is indeed responsible.
It is not unusual to find infants with immediate hypersensitivity to CMP whose first, or occasionally only, manifestation is refusal (37) to take the bottle of cow''s milk. Refusal may or may not be followed by other clinical manifestations.
Acute gastrointestinal manifestations, i.e., vomiting and diarrhea, may present individually or in association in 30% of cases (38). Immediate sensitization only very rarely causes prolonged diarrhea with malabsorption and anatomical impairment of the intestinal mucosa, although in some cases, these situations may be followed by immediate allergy.
Respiratory symptoms, in the form of recurrent wheezing, stridor, coughing or rhinoconjuntivitis, may appear in the context of systemic manifestations, but they are unusual as isolated symptoms and difficult to demonstrate when controlled challenge is performed (39).
There are no data in the literature on the incidence and prevalence of anaphylaxis due to CMP (40). The clinical manifestations of anaphylaxis are more frequent during lactation than at other ages. Death due to anaphylaxis is rare at this age, though it was reported by Finkelstein early this century (41).
The clinical presentations of anaphylaxis can be classified as follows:
1. Severe, life-threatening forms:
a) Glottic edema, which habitually occurs a few minutes after CMP intake. It is usually accompanied by facial angioedema and/or urticaria.
b) Anaphylactic shock, which usually begins during the first hour post-intake with a progressive decrease in arterial tension. It may or may not be accompanied by the symptoms described above.
2. Generalized presentations, affecting more than one organ. These forms are usually characterized by cutaneous symptomatology (42), with ery- thema, pruritus, urticaria and angioedema, accompanied by vomiting, acute abdominal pain, or respiratory difficulties. The angioedema may affect the eyelids, lips, or tongue.
DIAGNOSIS
The diagnosis of CMP allergy should be considered at two levels. The first is clinical diagnosis, the demonstration of the existence of an adverse reaction to CMP. This has two fundamental aspects: clinical history and the confirmation of the relation between the symptoms and the intake of cow''s milk. The second is the pathogenic diagnosis of the immunological mechanism, performed by demonstrating the presence of CMP-specific IgE antibodies.
However, testing the association between CMP and symptoms can be dangerous; this part of the clinical diagnosis should be left for last, after attempting to establish the immunological mechanism. The correct procedure is first to establish the clinical history (anamnesis, physical exploration and complementary examinations), then the pathogenic diagnosis (search for IgE antibodies) and finally the confirmatory diagnosis (via food challenge).
Clinical history
Clinical diagnosis requires a detailed account of the presence of family and/or personal history of atopy, feeding received, whether the infant was occasionally bottle-fed during the neonatal period and in the maternity ward, whether the mother breast-fed (exclusively or mixed, and duration), introduction of artificial feeding, and type of formula. Data should also be compiled on the age of onset of symptoms, type of symptoms, factors that precipitate symptoms, and the time interval between milk intake and the appearance of the clinical syndrome (2, 33, 44) (table III).
Table III | |
Anamnesis with suspected CMP allergy | |
| Family history of atopy. | |
| Personal history of atopy. | |
| Feeding: | |
| * mother''s milk. | |
| * Mixed. | |
| * Artificial. | |
| * Sporadic bottles. | |
| Age of onset of symptomatology. | |
| Interval between beginning of artificial feeding and onset of symptoms. | |
| - Interval between intake and appearance of symptoms: | |
| * Immediate: under 1 hour. | |
| * Intermediate: between 1 and 24 hours. | |
| * Delayed: after 24 hours. | |
| - Symptoms: | |
| * Cutaneous/mucosal: | |
| * Gastrointestinal. | |
| * Respiratory. | |
| * Anaphylactic shock. | |
A detailed physical exploration should be performed, including somatometry; if there are digestive symptoms, signs of malnutrition and/or malabsorption should be sought.
A thorough clinical history is an excellent indicator of the response to the food challenge later on.
Pathogenic diagnosis (search for IgE antibodies)
The search for CMP-specific IgE antibodies can be performed in complete cow''s milk and its protein fractions (*-lactalbumin, ß-lactoglobulin, bovine seroalbumin and casein). Finding selective IgE to the various protein fractions is of particular interest, given the possibility of finding subgroups of patients with CMP allergy with distinctive characteristics. Garcia Ara et al. (43) found that the increase in casein-specific IgE is related to a greater difficulty in reaching clinical tolerance during the evolution of CMP allergy. The extracts should be as pure as possible so as to avoid possible contamination among the various fractions.
Immediate skin tests
Skin tests are habitually performed using the prick test technique. In Europe intradermal test is
rarely used today, due to its lack of specificity. Skin tests are performed with a correctly standardized technique (45) and reliable extracts. In commercial extracts in regular use the concentration of cow''s milk and its protein fractions tend to be 5 mg protein/mL, with the exception of casein, which is 10 mg/mL. The sensitivity of the skin tests varies widely (41-100%), due to variations in age and the type of clinical manifestations of the study groups (2). In the study with the lowest sensitivity, the positive predictive value (PPV) is 89% and the negative predictive value (NPV) 77% (35).
Since a large percentage of children with CMP allergy may be sensitized to other foods (46), it is advisable to perform skin tests with the foods that most commonly produce sensitization in childhood, principally eggs and fish. Soy should also be tested since it may be used as a substitute nutrient in the diet of a child with CMP allergy, and beef on occasion as well, especially if sensitization to bovine seroalbumin has been detected (15).
In patients with atopic dermatitis, epicutaneous tests may well be useful in addition to the prick test. Isolauri and Turjanmaa (47) applied 20 mg of cow''s milk in wetted powder in a patch maintained in occlusion for 48 hours and read after 72-96 hours. They found the sensitivity of the test to be 61% and its specificity 81%; its application, with the prick test, significantly increased diagnostic reliability in atopic dermatitis.
Specific IgE in serum
The clinical value of determining specific IgE in serum in the diagnosis of immediate CMP allergy is similar to that of skin tests (2). The determination of specific IgE in patients with atopic dermatitis or dermographism is particularly important, since these patients cannot be given skin tests. In this situation, specific IgE has a high NPV. Sampson and Ho (48), in a study of children with atopic dermatitis, found a sensitivity of 100%, specificity 30%, NPV 100% and PPV 2%, compared with the food challenge. Caution is required in comparing results of studies that may have used different extracts and methods of determining specific IgE.
In addition, the value of specific IgE in serum may be a useful parameter in the follow-up of children in whom immediate CMP allergy is diagnosed, since falling IgE has been associated with the development of tolerance (43, 49).
As in the skin tests, CMP-specific IgE in serum is of no use in the diagnosis of delayed reactions, as in general these reactions are not IgE-mediated.
Other untested or less useful methods
The determination of CMP-specific IgG, or its subclasses, has been proposed as a diagnostic procedure for CMP allergy. However, identification of this immunoglobulin does not distinguish between patients who are sensitized to CMP and healthy individuals. It is well known that specific IgG seems to be a sign only of exposure, rather than of actual hypersensitivity (50). Some authors have found that IgE/IgG specific ratios may have a certain diagnostic or prognostic value (49), but these data require fuller evaluation.
Tests of cellular hypersensitivity, such as T-lym-phocyte proliferation tests (lymphoblast transformation test - LTT) to the antigen, have produced contradictory results, and although some significant data have been found in patients with atopic dermatitis (51), the diagnostic value of these tests has not been established. Similarly, the identification of lymphokines as the factor of inhibition of leukocyte migration (52) and their patterns of production in vitro after antigenic stimulus (53) are still in the experimental stage.
Other procedures, such as tests of histamine release, basophil degranulation, eosinophil cation protein, the eosinophil peroxidase test and studies of intestinal permeability are excessively complicated for use in everyday clinical practice and do not provide more data than other duly tested methods; in addition, some are highly nonspecific. Their clinical usefulness has not been confirmed, and so for the moment their application is limited to research.
Elimination-reintroduction diet
Elimination diets can be used in patients with chronic symptoms and positive skin tests and/or CMP-specific IgE. If the patient does not improve after a strict exclusion diet for two weeks, it is unlikely that CMP allergy is the cause of the symptoms. If the patient shows clear improvement after the exclusion diet, a food challenge should be performed. In infants, elimination of CMP from the diet is straightforward, but it is more difficult in children over a year old, since many foods contain small quantities of cow proteins that are not specified on labels.
Food challenges
Controlled food challenges establish the existence of current clinical sensitization. Controlled double blind challenges with placebo are considered the "pattern of reference" for confirming the existence of an adverse reaction to CMP. However, they are time-consuming and complicated, and there is no consensus on which technical procedure should be applied. A positive challenge only indicates the existence of an adverse reaction, and does not identify the underlying pathogenic mechanism.
Open or simple blind challenges may be sufficient if the result is negative or clearly positive, i.e., if the test induces objective symptoms in the infant. If the clinical manifestations are unclear, difficult to evaluate or have no immediate cause-effect relation, a double blind challenge is required. This is particularly indicated in atopic dermatitis (54), although some authors find no qualitative differences between open and double-blind challenges in children under the age of three (47).
There is a series of situations in which challenges should not be performed, due to diagnostic evidence of immediate CMP allergy, or to the danger of the procedure (55):
Generalized anaphylaxis or glottic edema related to the intake of CMP and the presence of specific IgE.
Clinical manifestations highly suggestive of CMP allergy, i.e., when all the following are present:
a) Urticaria and/or general angioedema.
b) Appearance of symptoms in the first 60 minutes after intake.
c) Repeated episodes of similar characteristics (two or more).
d) Positive skin tests (3 mm) and/or CMP-specific IgE in serum (0.35 kU/L).
e) Less than three months since the last clinical reaction.
During exclusive breast-feeding; the challenge should be delayed until the beginning of artificial feeding.
The challenge should always be performed in a hospital with reanimation equipment. Date and hour of administration should be noted carefully in the patient''s records, along with the product used, the quantity ingested, and any incidents of importance during the period of observation.
A two-stage double-blind challenge protocol, proposed by Baehler et al. (56), allows differentiation between immediate and delayed types of adverse reactions to CMP. On the first day, increasing, successive doses of milk or placebo are administered every 15 minutes: 0.5 mL, 1 mL, 2.5 mL, 5 mL,
10 mL, 20 mL, 30 mL and 60 mL. If there is no reaction, the patient is discharged after 4 hours. From the second day onwards, up to 250 mL of cow''s milk or placebo is administered per day. On the eighth day the product is crossed, until the fifteenth day. The test''s correlation with clinical history is 62.5% in the group of children who present immediate reactions and 28.8% in the delayed reaction group.
In open or single-blind challenges in infants the initial quantity administered varies between 2 and 5 mL, depending on the data from the clinical history and the result of the allergologic study; the dose is increased to 10 mL the same day. The milk used in the challenge is a 13% adapted initiation formula which is administered in isolation, i.e., not mixed with other foods. Successive doses of 25, 50 and 100 mL are then administered on different days (55). Faster rates of increase, in which the habitual dose is reached in one day, can also be used (35), although the risk of intense reactions will be greater. After feeding, the child remains under supervision for at least 3 hours. If there is no reaction, the formula is given at home and the test is considered negative. Doubtful challenges are repeated a week later (55).
Figure 1 shows an algorithm for diagnosis of the CMP allergy.
Fig. 1--Diagnostic chart flow in cow''s milk protein allergy.
FOLLOW-UP, EVOLUTION AND PROGNOSIS
Prognosis of the development of clinical tolerance is favorable in most infants and small children with immediate CMP allergy. Between 28% and 56% enter the stage of clinical remission after 1 year, 60-77% after 2 years, and 71-87% after 3 years (43, 46).
Many patients with CMP allergy continue to show positive skin tests even when they have reached the tolerance stage. Nor does CMP-specific IgE in serum disappear, although at the tolerance stage its values are usually lower, generally below 3.5 kU/L of CAP (43). For this reason, periodic challenges should be performed to test tolerance, as long as clinical and analytical data do not contraindicate it, at the ages of 12, 18 and 24 months, and subsequently every year. This follow-up is shown in table IV.
Table IV |
Follow-up protocol in immediate CMP allergy* |
| FIRST CHECK-UP: 3 months after first visit. Clinical history and physical examination. Control of beikost, administration of vitamins and vaccinations. |
| SECOND CHECK-UP: 6 months after previous review (or at the age of 1 year, if sooner). Clinical history, data concerning feeding, and physical examination. Allergological study, similar to initial study (prick tests are only required if a challenge is to be performed). If the patient is already 1 year old: controlled food challenge with a milk formula. Adapted to the clinical study of the patient; it should not be performed in cases of recent positive transgressions, at most 1 month before consultation). |
| THIRD CHECK-UP: at the age of 18 months. Clinical and allergological study, as in the second check-up including skin tests. Food challenge (if not performed in the second check-up). |
| FOURTH CHECK-UP: at the age of 2 years. Clinical and allergological study. Controlled food challenge. |
| SUCCESSIVE CHECK-UPS: every year, until tolerance is reached. Clinical and allergological study. Controlled food challenge. |
| (*) CMP allergy study protocol followed at the Allergy Service, "La Paz" Children''s Hospital, Madrid. |
Among indicators of poor prognosis are: reaching the age of 5 years without tolerating CMP, and the presence of high sensitization to casein (43) or other concomitant sensitizations. CMP allergy is in many cases the first proof of a genetic predisposition which in the future will manifest itself in new atopic illnesses. It has been observed that between 41% and 54% of children with CMP allergy develop allergy to other foods, and up to 28% to inhalants (35) before the age of 3 years. Some studies report that up to 80% develop allergy to inhalants before puberty (46).
TREATMENT
Elimination diet
Once diagnosis of immediate CMP allergy has been confirmed, a strict CMP-free diet should be administered. This is currently the only really effective treatment. A range of drugs (sodium chromoglycate, antihistamines, etc) have been used to prevent the appearance of symptoms, but without satisfactory results (57).
If the child is breast-fed, breast-feeding should be continued as long as possible; meanwhile, the mother should not consume cow''s milk, milk derivatives or other foods that may contain CMP. Infants with CMP allergy whose only food is cow''s milk require a CMP-free substitution formula, which will be described below. Beckost should be delayed until the age of 6 months, and foods with high allergenic power (in our geographical area, principally foods containing eggs, fish and nuts) should be avoided until the age of 2 years (2).
In older children cow''s milk substitutes are not strictly necessary, since other sources of protein are available. Nonetheless, the administration of vitamins, minerals especially calcium and trace elements should be carefully supervised.
Milk derivatives can be found in small quantities in a wide variety of foods, and family members and
carers should take great care to avoid them (table V). Unless sensitization is demonstrated and accompanied by clinical manifestations, there is no need to eliminate beef.
Table V |
| Elimination diet: milk-free and milk derivative-free diet Advice and observations |
| * The diet should omit cow''s milk and all dairy products: yoghurt, cheese, flan, custard, butter, cream, rice pudding, etc. * Read labels on food products with care. In the same category of products, some may contain CMP and others not. * CMPs may appear under a range of names: milk. sodium caseinate, calcium caseinate, potassium caseinate, magnesium caseinate, protein hydrolyzate, casein, whey, H4511, H4512, lactalbumin, lactoglobulin, lactose, lactic acid. * These substances are used in the production of most kinds of processed bread. Particular care should be taken with these products; ask your baker for more detailed information. * Products described as "non-dairy" often contain sodium caseinate. |
Substitution formulas
Formulas with a different source of protein can be used, such as soy, hydrolyzed formulas (of whey, casein, casein plus whey, soy plus pig collagen) or elementary formulas based on amino acids. Milk from other mammals such as goats and sheep should not be given, due to their similarities with cow''s milk (13, 14).
Soy protein-based formulas are potentially highly antigenic and can be used when there are no associated clinical manifestations of enteropathy or malabsorption. For some authors soy formulas are the treatment of choice for the CMP allergy; the most suitable alternatives are extensively hydrolyzed formulas when there is evidence that the infant is allergic to soy protein (58). Recently, a multicenter study in Italy (59) found that sensitization to soy occurs in no more than 6% of children with food allergy, and only a fifth of those had a positive challenge to soy.
Among therapeutic options are extensively hydrolyzed formulas based on cow''s milk proteins. However, given that highly sensitized infants may present adverse reactions to these hydrolyzates (60-62), prior evaluation is required. Before beginning the administration of an extensively hydrolyzed formula, its possible allergenicity should be assessed individually in each child via prick tests (because of their high NPV), with a fresh sample of the reconstituted formula. Tolerance of the formula should be tested by open food challenge, under the supervision of a specialist, before it can be used in normal feeding (2, 63). If prick tests are positive the challenge should be conducted with the precautions mentioned above in the description of the diagnosis of CMP allergy.
Anomalies of certain nutritional parameters have been described with these extensive hydrolyzates (for example, aminoacids, ureic nitrogen in the blood, retention and absorption of calcium and phosphorus) (64), but in the vast majority of infants, they have proved to be safe and efficient (2). The ESPACI position paper recommends extensively hydrolyzed formulas for the treatment of CMP allergy on the grounds of their safety and hypoallergenicity (63).
Partially hydrolyzed formulas should never be used in the treatment of CMP allergy, since a portion of their proteins (with all their allergenic power) remains intact. These formulas are known as hypoallergenics (HA) although the term is inaccurate, since, at the most, they could be called hypoantigenics or hypoimmunogenics. A recent study reported that these partially hydrolyzed formulas could produce allergic reactions in 50% of children with CMP allergy (65).
Soy and pig collagen hydrolyzates can also be used. Their taste is slightly more pleasant, and their price similar to other hydrolyzed formulas. In these products soy and pig collagen proteins are extensively hydrolyzed. They are relatively new, and studies of their clinical effectiveness are still required.
When these products fail, elemental formulas based on l-amino acids, glucose polymers and vegetable oils are used.
PREVENTIVE MEASURES
Prevention of CMP allergy cannot be separated from general preventive measures for allergic illnesses in newborns. Preventive measures should be strict and applied long-term, and so it is difficult to apply them to the whole population; indeed their application would be unnecessary for most infants. In the case of immediate allergy to CMP, the newborn at high atopic risk is the best candidate for preventive methods.
Any effective preventive activity should meet the following requirements: (a) it should predict high risk groups; (b) it should demonstrate the effectiveness of the strategies used; c) the strategies it uses should be admissible; (d) it should reduce adverse effects to a minimum; and (e) it should evaluate the cost/benefit ratio (66).
The data available confirm the effectiveness of a family history of atopy as a screening method for predicting the condition, but indicate that in isola-tion it is not particularly effective, and should in some cases be accompanied by another indicator. According to Zeiger (66) a history of atopy in the immediate family has a sensitivity of 40% and a specificity of 80% in predicting atopic disease.
Risk markers
IgE in cord blood seems to be the best marker of atopy, for a number of reasons: the fetus is able to synthesize IgE from the eleventh month of gestation; IgE in cord blood has been found from the 37th week of gestation onwards; it does not cross the placental barrier; there is a strong correlation between IgE and allergy, and infants with high IgE are more likely to develop atopic illness. Levels of IgE in cord blood may be higher in blacks, in males, in infants born in September or in the autumn months in general, and in infants born to smoking mothers (although this point is controversial, as some studies found no relation), and in infants whose mothers consume alcohol, have helminthic parasites or have been administered certain drugs (progesterone and ß-blockers such as metoprolol) (67, 68). Cut-off points for cord blood IgE vary between 0.5 and 0.9 kU/L (67, 69, 70). The
choice of these levels depends on the prevention me-thods to be applied: low levels (with higher sensitivity) are preferred if straightforward methods are used, and higher cut-off points (with higher specificity) when the measures are complex.
The determination of cord blood IgE, together with a well-documented family history of atopy, are the markers with the best predictive value, and are the most reliable indicators for selecting candidates for clinical studies with primary preventive measures (69-72). Today, given the low sensitivity of the methods available, a systematic search for atopy in the general population based on the determination of IgE in cord blood or on other procedures cannot be recommended (73).
Other markers of atopy have been proposed and used, both in cord blood and in newborns and infants, but none of them seems to be a good method for systematic searches due to their excessively low positive predictive value, sensitivity, and specificity. Furthermore, in general they are laborious, expensive and of little real clinical use (67, 69).
General preventive measures
In all newborns those at high-risk and others certain general hygienic and environmental measures should be applied: encouraging breast-feeding as long as possible; discouraging smoking on the part of the pregnant mother, and avoiding passive smoking in the newborn. But in children identified as high-risk on the basis principally of family history, further preventive measures should be taken: contact with environmental allergens such as animal fur, mites, dust, mold, etc. should be avoided,
breast-feeding should be recommended and breast-feeding mothers should avoid certain foods.
The preventive measures aim to avoid either sensitization and the development of the allergic illness or the manifestations of the illness if the individual is already sensitized (66). Once the fetus has been classified as high-risk, preventive measures should be implemented as early as possible, even during gestation (74).
In order to minimize possible intrauterine sensitization to food antigens, the reduction in quantity or avoidance of certain foods such as milk, eggs, fish, and peanuts has been suggested during the last 3 months of pregnancy, However, controlled studies found no preventive effect as the result of modifying the pregnant woman''s diet (75), and so these restrictive diets are not recommended; indeed, such diets may even generate deficiencies, in the mother or the fetus. The only restriction during gestation that has been proven to be efficient is the avoidance of smoking, since smoking has been demonstrated to favor the development of atopy, fundamentally asthma, in children (72).
Regulation of diet in risk children
Breast-feeding
Mother''s milk is the ideal food for all newborns, as it provides nutritional, immunological, physiological and psychological benefits. It should always be recommended, and cases in which there is a risk of atopy are no exception, in spite of the fact that small quantities of food antigens have been detected in human milk (25). It has been observed that children who are exclusively breast-fed for a minimum of 6 months, and whose mothers avoid potentially allergenic food, run a lower risk of developing food sensitization and atopic dermatitis in the first years of their lives, although these measures do not appear to influence the development of respiratory illnesses of allergic etiology during breast-feeding (7, 76, 77). In a series of 150 children followed up over a period of 17 years, it was found that breast-feeding had a preventive action on atopic dermatitis, food allergy, and asthma (78).
Breast-feeding can protect against the appearance of allergic disease via a range of mechanisms (table VI); thus the mother not only influences her child genetically, but is herself a highly important environmental factor at the beginning of the child''s life (79, 80).
Table VI |
Possible protective mechanisms of breast-feeding |
| Protects against infections. |
| Stimulates maturation of the immunological system. |
| Low allergen content. |
| Transference of passive immunity. |
| Influence on intestinal flora. |
When a newborn at risk is to be breast-fed, bottles of CMP formula should be avoided. On many occasions a bottle is given during the first hours or days of life, and this may induce sensitization in these predisposed children, as mentioned earlier (see the section Factors that condition and favor sensitization). Equally, breast-feeding mothers should avoid the most allergenic foods (cow''s milk and eggs, above all), should postpone complementary feeding until the infant reaches the age of 6 months, and should not introduce foods with high allergenic power until the child is at least 1 year old (2).
Substitution formulas
When an infant at risk for atopy cannot be breastfed, or if the mother produces insufficient quantities of milk, feeding should be supplemented with a suitable formula. Artificial feeding from birth does not seem to facilitate IgE-mediated sensitization to CMP (28, 29), but it does increase the incidence of clinical manifestations of atopy in later life (77, 78). The ideal substitution formula for the prevention of immediate CMP hypersensitivity is nutritionally adequate, has a pleasant taste, is inexpensive and easily available, and is non-allergenic, i.e., totally free of CMP and peptides with allergenic epitopes.
There are a number of possibilities, such as soy formulas, and partially or extensively hydrolyzed CMP formulas (based on casein, whey, casein plus whey, soy and pig collagen) (81). Soy formulas contain some intact proteins with a high degree of possible sensitization, although in fact, this sensitization is relatively infrequent (59). Partially hydrolyzed formulas contain varying proportions of potentially sensitizing intact proteins (82). Extensively hydrolyzed formulas seem to be better suited, given their lower levels of antigenicity and allergenicity (82-84).
INTOLERANCE OF COW''S MILK PROTEINS
This is a transitory clinical situation found typically in infants, characterized by the presence of diverse gastrointestinal symptoms with variable repercussions for the patient''s nutritional status. Symptoms are induced by CMP intake, improve when these proteins are eliminated from the diet, and recur after re-exposure. The pathogenesis of CMP intolerance is not clear, though in certain situations an immunological mechanism is suggested (85). Equally, anatomical lesions of the intestine, when present, are of variable localization and intensity.
A similar situation may arise (though more rarely) in relation to other foods such as soy (86), eggs (87), rice (88, 89), chicken and fish (88), either in association with cow''s milk or not.
The symptoms are variable, beginning in almost all cases during the first week of life. In general, they are progressive. Diarrhea is the most frequent sign, although its characteristics are diverse, ranging from the persistent presence of soft, abundant feces to episodes of explosive, liquid diarrhea. The presence of blood in feces indicates colic or rectocolic involvement. Vomiting, abdominal distension and irritability are non-specific symptoms with a multitude of possible causes, although they may be the first indicators of the illness, as indeed a flat weight curve may be. Physical and analytical signs of malab sorption or a stationary growth curve may be observed.
CMP intolerance is not infrequently associated with gastroesophageal reflux (GER), possibly secondary to the slowing of gastric emptying after intestinal injury. Recently, in a series of 204 infants with GER demonstrated by 24 hour pHmetry and histology of esophageal mucosa (90), double-blind challenge detected the presence of CMP intolerance in 84 subjects. This association should therefore be suspected in a infant with GER accompanied by altered bowel movements.
Anatomical and clinical forms
When CMP intolerance is accompanied by cow''s milk sensitive or cow''s milk-induced enteropathy (91) duodenojejunal biopsy may reveal variable, non-specific injuries of the small intestine mucosa. In recent years their incidence has gradually decreased (92).
In most cases in untreated children moderate or intense partial atrophy is found in patches, alternating with normal or less affected areas, with moderate infiltration of intraepi-thelial lymphocytes, but not of eosinophils. Less frequently subtotal atrophy may be observed, as in gluten-induced celiac disease. These alterations remit with a diet free of cow''s milk or the offending nutrient, and reappear with their reintroduction.
Immunohistochemical analysis (93) has detected an increase in activated CD4+ cells and intraepithelial CD8+ cells in the lamina propria in the small intestinal mucosa, which return to normal with the exclusion diet, and revert to previous levels with the food challenge. These findings may indicate the involvement of these activated cells in the production of the patients'' mucosa lesions, possibly via the release of cytokines.
Another well-characterized form is allergic colitis (94), an entity that predominantly affects newborns and infants during the first months of life. It presents as diarrhea with mucs and blood or rector-
raghia, in the absence of rectal fissure or infectious gastroenteritis. Rectosigmoidoscopy shows erythematous mucosa, with or without loss of the vascular patterns, ulcerations or bleeding. On occasion it may be granulous, suggesting lymph node hyperplasia. As in enteropathy, injuries in the form of patches usually alternate with areas of normal mucosa (95). The principal histological finding is an infiltrate of eosinophils (96), which may be directly responsible for the tissue lesion, but the ultimate reason for this infiltration and activation is unknown. It is not a specific finding, as eosonophilic infiltration can also be found in parasitosis, vasculitis, intestinal inflammatory illness, or radiation. Unlike CMP-sensitive enteropathy, the frequency of this disorder in Spain seems to be increasing (95).
Onset occurs shortly after the introduction of cow''s milk or, less frequently, after the introduction of other proteins such as soy, and may be acute, occurring a few hours after beginning feeding. On other occasions there is a longer interval between the introduction of cow''s milk and onset of the symptoms. It may also appear in children who are exclusively breast-fed, in whom the antigen is transmitted via the mother''s milk (97); in these cases the symptoms may be less serious, and may appear later (98).
Diagnosis
Since there are cases of CMP intolerance with malabsorption, but without manifest enteropathy, the diagnosis cannot be based on small intestine biopsy. Equally, short-term food challenge followed by intestinal biopsy may give incorrect results. Laboratory or biochemical methods also have insufficient specificity and sensitivity.
Diagnosis is generally based on clinical criteria, by means of elimination and reexposure to cow''s milk. The challenge is performed habitually after 2 or 3 months of the elimination diet, mainly after the age of 6 months. Some authors (99) have applied anatomical and clinical criteria, including small intestinalbiopsies before and after CMP challenge. However, there is not always good correlation between clinical response and histological relapse after the challenge. Furthermore, the clinical response may be difficult to evaluate, since in many cases, symptoms gradually disappear after elimination and may take several days to reappear after reexposure. For these reasons, and also bearing in mind the self-limiting nature of the process, in clinical practice duodenojejunal biopsy for diagnosis is not frequent. Rectosigmoidoscopy, together with the evaluation of several biopsy samples, may be useful in severe cases of colitis and in patients who do not improve on the elimination diet.
Due to the injury of the intestinal surface in the villi, there may be a secondary deficiency in disaccharides (lactase). This factor contributes to the perpetuation of the symptoms and complicates the differential diagnosis between CMP intolerance and lactose intolerance. Lactose intolerance should be ruled out before performing a challenge for the definitive diagnosis of CMP intolerance.
Factors favoring intolerance
The importance of acute gastroenteritis as a predisposing factor has not been established, although it is a frequent antecedent and some authors believe that the prolonged or even intractable diarrhea that may follow some types of gastroenteritis in infants are due to temporary CMP-induced enteropathy (100). It also appears that early artificial feeding is an important risk factor: most patients had not been breast-fed, or had been breast-fed only for a short time (101). It may be that the lower incidence currently observed in some of these processes is related to the greater frequency and duration of the breast-feeding, and to the higher quality of the formulas used.
Skin and serum tests do not normally detect CMP-specific IgE antibodies in infants with CMP-sensitive enteropathy or colitis. Some patients present low levels of CMP-specific IgE antibodies, but this finding is usually transitory, and indeed sometimes they are only detected once clinical tolerance of CMP has been achieved (102). These data seem to indicate that immediate hypersensitivity, if it exists, is not an important mechanism in causing or maintaining CMP enteropathy or colitis.
Evolution and prognosis
Habitually, CMP intolerance is a self-limiting process in time. Under a CMP-free diet (generally casein or seroprotein hydrolyzates) both the clinical manifestations and anatomic lesions, if they exist, tend to remit after a few months and in practically all cases before the age of 2 years (103, 104).
When the food challenge is performed (102), CMP-sensitive enteropathy or colitis in infants is occasionally observed to coexist with, or be followed by, the appearance of symptoms characteristic of an immediate hypersensitivity reaction, with extradigestive signs such as urticaria, angioedema, and evidence of CMP-specific IgE antibodies. The presence of immediate hypersensitivity to CMP, with high titers of specific IgE, has also been observed in a case of necrotizing enterocolitis in a newborn child (105), though its relevance to the onset of the illness was not determined.
In some cases allergic colitis in the infant may be a predisposing factor for the appearance of inflammatory bowel disease some years later (106).
Treatment
Treatment is based on substituting cow''s milk formulas with others that do not contain CMP. Only nutritionally complete formulas are recommended. Formulas of low osmalarity should be chosen, above all for very young children. Lactose intolerance is usually accompanied by intolerance to the protein, and so lactose should also be eliminated from the diet.
Soy derivatives are not recommended, since as many as 15% of children with enteropathy may also present intolerance to soy (107).
The substitution treatment of choice is based on extensively hydrolyzed CMP formulas. Formulas based on casein, seroproteins or a mixture of the two all appear to be equally effective. Soy and pig collagen hydrolyzates can also be used, but no independent evaluation of these types has been done to date.
If intestinal absorption is altered, hydrolyzates made from easily absorbed fats (a percentage of them in the form of mid-chain triglycerides-MCT) should be used, and their carbohydrates should be modified. Lactose should be replaced by glucose polymers or dextrinomaltose.
When patients do not tolerate these products (108, 109) or if intestinal impairment is severe, elementary formulas based on L-amino acids should be used, even in enteral or in parenteral nutrition.
Prevention
There is no way of identifying patients at risk for predisposition to primary CMP intolerance. In any case, it has not been demonstrated that atopic children, or children at risk for atopy, show a greater predisposition than others towards CMP intolerance.
For the prevention of secondary CMP intolerance, the risk situations noted above should be avoided, as should early artificial feeding and infectious gastroenteritis. For this reason, prolonged breast-feeding until at least 6 months is the best preventive measure available. Equally, in artificially fed children, the use of adapted formulas, above all after acute gastroenteritis, is an effective measure for preventing secondary enteropathies (107).
CMP-FREE SUBSTITUTION FORMULAS
Soy protein-based formulas (table VII)
| Table VII | |||||
| Soy formulas (I) | |||||
| BRAND NAME (Laboratory) CHARACTERISTICS | ALSOY (Nestlé) | ISOMIL (Abbott) | MILTINA S (Milte) | NUTRIBEN SOY SMA (Alter) | NUTRISOY (Nutricia) |
| Energy value (Kcal/100 mL) | 67 | 68 | 70 | 67 | 66 |
| PROTEINS (g/100 mL) % calories Protein source | 1.9 11.3 Soy | 1.8 10.5 Soy | 1.9 11 Soy | 1.8 10.7 Soy | 1.8 11 Soy |
| Taurine | yes | yes | yes | yes | yes |
| CARBOHYDRATE (g/100 mL) % calories Carbohydrate source | 7.4 44.1 Dextrino- maltose 100% | 6.9 40.5 Saccharose Corn syrup | 7.7 44 Gucose 13% Dextrino- maltose 87% | 6.9 41.1 Glucose 100% | 6.7 40 Dextrino- maltose 100% |
| LIPIDS (g/100 mL) % calories Fat source | 3.3 44.3 Vegetable fat 100% | 3.69 21.7 Vegetable fat 100% | 3.5 45 Vegetable fat 100% | 3.6 48.3 Vegetable fat 100% | 3.6 49 Vegetable fat 100% |
| *6/*3 Linoleic acid/Linolenic acid | 10.2 | 8.5 | 10 | 13.8 | 5 |
| Carnitine | yes | yes | yes | yes | yes |
| Iron (mg/100 mL) | 0.8 | 1.03 | 0.97 | 0.8 | 0.8 |
| Ca/P Ca (mg/100 mL) P (mg/100 mL) | 1.4 60 43 | 1.4 70 50 | 2 49 24 | 1.34 67 50 | 2 54 27 |
| Osmolarity (mOsm/L) Osmolality (mOsm/g H2O) | 170 | 175 194 | 200 | 180 | |
| Presentation | 450 g tin | 400 g tin | 400 g tin | 430 g tin | 400 g tin |
| Soy formulas (II) | |||||
| BRAND NAME (Laboratory) CHARACTERISTICS | PROSOBEE (Mead Johnson) | PULEVA V (Abbott) | SOM 1 (Milupa) | SOM 2 Milupa | VELACTIN (Novartis Nutrition) |
| Energy value (Kcal/100 mL) | 67 | 68 | 70.3 | 75 | 68 |
| PROTEINS (g/100 mL) % calories Protein source | 2 12 Soy | 2 11.7 Soy | 2 10.8 Partially hydrolyzed soy | 2.3 12.2 Soy | 2.1 12 Soy |
| Taurine | yes | yes | yes | No | yes |
| CARBOHYDRATE (g/100 mL) % calories Carbohydrate source | 6.6 40 Glucose polymer 100% | 7.7 45.2 Dextrino- maltose 100% | 7.4 40.2 Glucose polymer 91% Starch 9% | 8 42.4 Glucose polymer 100% | 8.2 48 Dextrino- maltose 91.4% Starch 3.6% Other 4.8% |
| LIPIDS (g/100 mL) % calories Fat source | 3.6 48 Vegetable fat 100 % | 3.3 42.3 Animal fat 51.8% Vegetable fat 42.8% MCT 5.3% | 4 48.9 Vegetable fats 100% | 3.8 45.3 Vegetable fats 100% | 3 40 Vegetable fat 80 % MCT 20% |
| *6/*3 Linoleic acid/Linolenic acid | 9.5 | 10.8 | 10.48 | 5.3 | 65.5 |
| Carnitine | yes | yes | yes | No | yes |
| Iron (mg/100 mL) | 1.2 | 1.4 | 1 | 1.2 | 1.3 |
| Ca/P Ca (mg/100 mL) P (mg/100 mL) | 1.2 64.22 50.7 | 1.8 58 31.7 | 1.5 56 36.4 | 1.6 98 59 | 2 70 35 |
| Osmolarity (mOsm/L) Osmolality (mOsm/g H2O) | 181 | 150 | 250 | 259 | 135 150 |
| Presentation | 400 g tin | 400 g tin | 400 g container | 400 g container | 400 g tin |
May 1998 (Information provided by the manufacturers). | |||||
Soy is a member of the pulse family. Its proteins are principally globulins (85%), which do not cross-react with CMP (reviewed in 110). Soy has been used as a milk substitute in children for almost a hundred years. However, in the 1950s soy-based formulas were associated with nutritional deficiencies in vitamins A, K and B12, the development of goiter, and intolerance to carbohydrates; this led to the development of a second generation of formulas based on isolated soy protein supplemented with l-methionine, taurine and l-carnitine, which soy lacks. Daily vitamin requirements were also added.
There are no long-term metabolic studies of these formulas. Short-term studies have shown that formulas prepared from isolated soy protein or soy protein concentrate are nutritionally adequate for children and adults, but not suited to newborns and infants; for these very young children the formulas need to be supplemented with sultur-containing amino acids such as methionine (111).
Soy protein isolates are derived from fat-free soy grains, using a slightly alkaline aqueous solution to extract the proteins, and then adjusting the pH to the isoelectric point of 4.5 so that they precipitate. The proteins are heat-treated in order to curb the activity of trypsin and hemaglutinin inhibitors. The mixtures of fats in these soy formulas are usually the same as those used in formulas made from cow''s milk by commercial companies. In the main, they are a mixture of vegetable oils. The carbohydrates used are dextrinomaltose, corn, starch and saccharose. None of these products contain lactose.
Isolated soy protein contains approximately 1.5% phytic acid (mio-inositol-hexaphosphoric acid). The phytates formed can bind to zinc and make it unusable; they also inhibit the absorption of iron (112). Formulas for infants based on isolated soy protein are generously enriched with zinc and provide relatively large quantities of iron. The fact that growth is normal suggests that zinc utilization is adequate, and iron content is similar in infants fed with these artificial milks and in infants that receive CMP-based iron-enriched products.
Isolated soy protein formulas are cheaper and taste better than hydrolyzed milk protein-based formulas. Parents should be aware that shops and supermarkets sell a range of nutritionally incomplete soy products, many of which contain only soy and water, without any supplementation, and so they cannot be used as cow''s milk substitutes for infants and small children.
Hydrolyzed formulas (tables VIII and IX)
| Table VIII | ||||||
| Partially hydrolyzed formulas | ||||||
| BRAND NAME (Laboratory) CHARAC- TERISTICS | APTAMIL HA with Milupan (Milupa) | ENFALAC LS (Mead Johnson) | MILTINA HA (Milte) | MODAR MIX (Novartis Nutrition) | NATIVA (Nestlé) | NIDINA HA (Nestlé) |
| Energy value | 77 | 67.6 | 70 | 70 | 67 | 67 |
| (Kcal/100 mL) PROTEINS (g/100 mL) % calories Protein source Casein/Seroproteins | 1.5 8.8 Casein 50% Sero- proteins 50% 50/50 | 1.5 9 Casein 40% Sero- proteins 60% 40/60 | 1.8 10 Sero- proteins 100% 0/100 | 1.7 9.7 Casein 40% Sero- proteins 60% 40/60 | 1.7 10.1 Sero- proteins 100% 0/100 | 1.6 9.5 Sero- proteins 100% 0/100 |
| free AA/peptides | 3.8 % free AA | 4.3% free AA and dipeptides | 4.3% free AA and dipeptides | |||
| Taurine | yes | yes | yes | yes | yes | yes |
| CARBOHYDRATE (g/100 mL) % calories Carbohydrate source | 7.2 42.5 Lactose* 100% | 6.9 41 Lactose* 100% | 7.2 41 Lactose* 50% Dextrino- maltose 44.4% Glucose 5.6% | 7.6 43.4 Lactose* 61.8% Dextrino- maltose 38.1% | .96 41.1Lactose* 100% | 7.4 44.1 Lactose* 70% Dextrino- maltose 30% |
| LIPIDS (g/100 mL) % calories Fat source | 3.6 48 Vegetable fat Vegetable fat LCP | 3.7 50 Vegetable fat 100% | 3.8 49 Vegetable fat 100% | 3.5 45 Vegetable fat 100% | 3.6 48.3 Vegetable fat 97.3% Animal fat 2.7% | 3.4 45.6 Vegetable fat 97% Animal fat 3% |
| *6/*3 Linoleic acid/Linolenic acid | 9.06 | 9.6 | 10 | 13 | 11.4 | 11.3 |
| Carnitine | yes | yes | yes | yes | yes | yes |
| Iron (mg/100 mL) | 0.8 | 0.4 | 0.7 | 1 | 0.8 | 1.2 |
| Ca/P Ca (mg/100 mL) P (mg/100 mL) | 1.8 61.8 33.8 | 1.5 45 30 | 1.7 60 35 | 1.5 52.8 34.9 | 1.9 41 21 | 1.9 38 20 |
| MW (Dalton) % < 500 500 - 1000 1000 - 5000 > 5000 | 99.9 (< 10 000) 66.4 (< 1000) 30.1 3.5 | 21.88 33.62 43.95 0.56 | 42 12 40 6 | 29.2 37.2 33.6 0 | 19 (140-600) 52.6 (600-2500) 22.5 (2500-5000) 6.1 | 19 (140-600) 52.6 (600-2500) 22.5 (2500-5000) 6.1 |
| Osmolarity (mOsm/L) Osmolality (mOsm/g) H2O | 310-350 | 281 | 250 | 270 312 | 280 | 220 |
| Presentation | 400 g tin | 400 g tin | 400 g tin | 400 g tin | 400 g tin | 400 g tin |
| * Lactose may be contaminated by CMP. May 1998 (Information provided by manufacturers). | ||||||
CMP hydrolyzed formulas have been used successfully for more than 50 years as the main source of nutrition in infants with a range of diseases. In particular, they have been used as a substitute in the feeding of infants with CMP allergy and intolerance. Their use is based on the premiss that these predigested proteins, when ingested in the form of amino acids and small peptides, may provide the organism with nutrients whose antigenicity and allergenicity are reduced.
The hydrolyzates used are mainly based on CMPs: either casein, whey, or a mixture of the two. Hydrolyzates of another protein source (soy and pig collagen) are also available on the market (tables VIII and IX).
| Table IX | ||||
| Extensively hydrolyzed formulas (I) | ||||
| BRAND NAME (Laboratory) CHARAC- TERISTICS | ALFARÉ (Nestlé) | ALMIRÓN PEPTI (Nutricia) | BLEVIMAT FH (Ordesa) | DAMIRA (Novartis Nutrition) |
| Energy value (Kcal/100 mL) PROTEINS (g/100 mL) % calories Protein source | 74 2.5 13.5 Seroproteins 100% | 67 1.6 9 Seroproteins 100% | 73 1.9 10.5 Casein 40% Seroproteins 60% 40/60 | 65 1.8 12 Casein 40% Seroproteins 60% 40/60 |
| Free AA/peptides | 20/80 | 20/80% | < 20% free AA | 5.25% of free AA |
| Taurin | yes | yes | yes | yes |
| CARBOHYDRATE (g/100 mL) % calories Carbohydrate source | 7.8 42.1 Dextrinomaltose 87.1% Starch 11.5% Lactose* 1.2% | 69 42 Dextrinomaltose 62% Lactose* 38% | 7.4 41 Dextrinomaltose 95% Early potato starch 5% | 8.2 50 Dextrinomaltose 89.02% Starch 9.7% |
| LIPIDS (g/100 mL) % calories Fat source | 3.6 43.7 Vegetable fat 25% Dairy fat* 27.7% MCT 47.2% | 3.6 49 Vegetable fat 100% | 3.9 48.5 Vegetable fat 100% MCT 15% | 2.8 38.7 Vegetable fat 78.5% MCT 21.4% |
| *6/*3 Linoleic acid/Linolenic acid | 23.6 | 5.3 | 9.6 | 14.3 |
| Carnitine | yes | yes | yes | yes |
| Iron (mg/100 mL) | 0.9 | 0.5 | 0.8 | 1 |
| Ca/P Ca (mg/100 mL) P (mg/100 mL) | 1.5 60 38 | 2 54 27 | 1.7 64.4 36.4 | 1.9 63 33.2 |
| MW (Dalton) in % < 500 500 - 1000 1000 - 5000 > 5000 | 18-22% (< 150) 45-52% (150-500) 12-19 (500-2500) 11-15 (> 2500) 0.1 (> 6000) | 86 (< 1500) 10 (1500-3500) 2 (3500-6000) 2 (> 6000) | 88.8 (< 1000) 9.2 2 | 85% (300 - 3000) 33.5 34.5 31 0 |
| Osmolarity (mOsm/L) Osmolality (mOsm/g H2O) | 200 | 260 | 190-200 209-220 | 190 210 |
| Presentation | 400 g tin | 450 and 900 g tins | 400 g tin | 400 g tin |
| * Lactose and dairy fat may be contaminated by CMP. May 1998 (Information provided by the manufacturers). | ||||
Protein hydrolyzates are obtained with three main techniques: heat-treatment, enzymatic hydrolysis and a combination of the two (113).
Heat treatment affects the structure of the protein, facilitating its hydrolysis and producing a
marked reduction in the allergenicity of the whey proteins, but not of the casein. The antigenicity of casein does not change after heat treatment at 121° C during 15 minutes, whereas boiling whey proteins for 30 minutes significantly reduces their antigenicity and immunogenicity. Enzymatic hydrolysis causes a progressive destruction of the proteins, including the sequential epitopes. It is usually necessary to include ultrafiltration to eliminate the proteins and peptides of high molecular weight and the residual enzymes used for their hydrolysis.
With heat treatment, the larger part of the secondary structure of the proteins disappears. However, on its own heat treatment does not achieven a sufficient level of hypoantigenicity and hypoallergenicity, unless the proteins are so denatured that their nutritional value is altered.
Enzymatic hydrolysis is habitually performed with a mixture of endopeptidases and exopeptidases. It does not destroy amino acids, and so the nutritional value of the protein substrate is maintained (113). Its duration and the choice of enzymes used lead to different degrees of protein fragmentation, giving rise to a range of free amino acids and peptides of different sizes. Partial hydrolysis produces segments of long peptides. Extensive hydrolysis produces a mixture of long and short peptides and free amino acids. Depending on its degree, hydrolysis generates either extensively hydrolyzed products (in which all peptides have a molecular weight of under 5000 Da, and most under 1500 Da) and partial hydrolyzates, in which a small percentage of peptides have a molecular weight of over 5000 Da (tables VIII and IX). Fur-thermore, these partially hydrolyzed formulas contain a certain proportion of non-degraded or partially degraded proteins, with molecular weights between 8 and 40 kDa (114). Obviously, the lower the antigenicity and allergenicity, the smaller the peptides. In recent years these products, especially partial hydrolyzates, have begun to be considered hypoallergenic formulas (H.A. formulas).
| Table IX | |||||
| Extensively hydrolyzed formulas (II) | |||||
| BRAND NAME (Laboratory) CHARACTE- RISTICS | NIEDA PLUS (Abbott) | NUTRAMIGEN (Mead Johnson) | PEPTINAUT Junior (Nutricia) | PREGESTIMIL (Mead Johnson) | PREGOMIN (Milupa) |
| Energy value (Kcal/100 mL) | 69 | 67.6 | 67 | 67.6 | 75 |
| PROTEINS (g/100 mL) % calories Protein source Casein/ Seroproteins | 2.1 12.1 Seroproteins 100% 0/100 | 1.9 11 Casein 100% 100/0 | 1.8 10.7 Seroproteins 100% 0/100 | 1.9 11.2 Casein 100% 100/0 | 2 10.6 Pig collagen and soy |
| Free AA/peptides | 45/55 | 20/80 | 45/55 | ||
| Taurine | yes | yes | yes | yes | yes |
| CARBO- HYDRATE (g/100 mL) % calories Carbohydrate source | 8 46.3 Dextrino- maltose 100% | 7.4 44 Glucose polymers 79% Corn starch 21% | 6.8 40.5 Dextrino- maltose 100% | 6.9 40.8 Glucose polymers Modified starch Dextrose | 8.6 45.9 Glucose polymers 79% Pregelatin. starch 21% |
| Fat source | Vegetable fat 88% MCT 12% | Vegetable fat 100% | Vegetable fat 100% MCT/LCT: 50/50 | Vegetable fat 100% MCT/LCT: 55/45 | Vegetable fat 100% |
| LIPIDS (g/100 mL) % calories */*3 Linoleic acid/Linolenic acid | 3.1 40.4 10.3 | 3.4 45 10.7 | 3.6 48.5 7.3 | 3.8 48 14.5 | 3.6 43.3 10.4 |
| Carnitine | yes | yes | yes | yes | yes |
| Iron (mg/100 mL) | 1.1 | 1.22 | 0.9 | 1.2 | 1.8 |
| Ca/P Ca (mg/100 mL) P (mg/100 mL) | 1.6 60.6 36.8 | 1.5 63.5 42.6 | 2 54 27 | 1.5 63 42 | 1.96 57 29 |
| MW (Dalton) in % < 500 500 - 1000 1000 - 5000 > 5000 | 77.8 (< 1200) 21.2 (1200 - 3400) 0.98 (3400 - 5000) 0.08 | 67 32.5 0.5 0 (>1500) | 86% (< 1500) 10 (1500-3500) 2 (3500-6000) 2 (> 6000) | 67 32.5 0.5 0 (> 1500) | 00% < 5000 |
| Osmolarity (mOsm/L) Osmolality (mOsm/g H2O) | 200 | 260 290 | 185 | 300 | 195 |
| Presentation | 400 g tin | 400 g tin | 450 g tin | 450 g tin | 400 g tin |
| May 1998 (Information provided by the manufacturers). | |||||
Often, enzymatic hydrolysis produces bitter peptides. The bitterness of the taste depends on the enzyme used, the protein substrate and the length of hydrolysis. The taste can be improved by careful choice of the enzyme system, or by using processes to reduce bitterness, such as extraction with solvents or filtration using activated carbon. In partial hydrolyzates, which have a lower degree of hydrolysis, taste, smell and color are all better.
Extensive hydrolyzates are hypoimmunogenic and hypoallergenic. Partial hydrolyzates are hypoimmunogenic, but not hypoallergenic (64) (table X). It has not been convincingly proved that partial hydrolyzates can prevent IgE-mediated CMP sensitization in children at high risk for developing an atopic illness (82, 115). In addition, partially hydrolyzed formulas contain small quantities of intact CMP and can therefore trigger symptoms in around 50% of sensitized children (65). Mäkinen-Kiljunen and Sorva (116) detected ß-lactoglobulin in seven different formulas of CMP hydrolyzates (casein, whey and mixtures). The quantity of ß-lactoglobulin was 40000 times greater in the partial hydrolyzates than in the extensively hydrolyzed formulas.
Table X | ||||
Characteristics of CMP substitute formulas (CMP(*) | ||||
CMP hydrolyzates | ||||
| extensive | partial | Soy | Aminoacids | |
| Immunogenicity | - | ± | ± | - |
| Allergenicity | ± | +++ | ± | - |
| CMP | - | ++ | - | - |
| Epitopes that react | ||||
| with CMP | ± | +++ | - | - |
| Nutritionally adequate | ? | ? | + | ? |
| Pleasant taste | - | + | + | - |
| Low cost | - | + | + | - |
| (*) Adapted from ref. 64. | ||||
In some extensively hydrolyzed formulas the fats are also modified by the addition of MCT (useful in cases of intestinal malabsorption) and in almost all these formulas the carbohydrates have been modified, replacing, lactose with dextrinomaltose, starch and glucose polymers (in cases of secondary intolerance of lactose), although some retain a small percentage of lactose in their composition. Partially hydrolyzed formulas usually retain lactose as their main or only carbohydrate component. This lactose may be contaminated by intact CMP.
Requisites for hypoallergenic hydrolyzates
In principle, a hypoallergenic formula should contain fewer allergens than a normal formula, but not necessarily none at all. However, its possible allergen content should be low enough to ensure perfect clinical tolerance when administered to a child with immediate CMP allergy, without increasing sensitization. So all formulas designed for treatment of patients with CMP allergy or intolerance, or for prevention of the conditions, must undergo a series of studies that demonstrate their effectiveness.
1. Preclinical studies, to demonstrate a significant reduction in the antigenicity of the formula''s source of nitrogen, via physicochemical and immunochemical tests:
a) Determination of the molecular weights of its peptides: as a general rule, the lower the molecular weight of the protein hydrolyzate, the lower its residual antigenicity, and therefore the lower its potential allergenicity. The test uses gel filtration, high resolution liquid chromatography, and electrophoresis in polyacrylamide gel with sodium laurylsultate.
b) Verification of the reduction in immunogenicity and antigenicity using immunochemical procedures in vivo and in vitro, although naturally it is not possible to extrapolate the antigenicity and allergenicity results obtained in laboratory animals to humans, even less so in patients with prior CMP sensitization. The response of antibodies in the experimental animal to the injection of the product (117) and analysis in vitro of the interaction of the hydrolyzate with preformed antibodies for the native protein can give a direct quantitative or semiquantitative estimate of residual antigenicity (116).
2. Nutritional characteristics: these formulas should ensure growth similar to that obtained in breast-fed children or in children fed conventional formulas, and comparable biochemical values. From a nutritional point of view, the formula should be as similar as possible to mature human milk, above all as regards amino acid composition (118) and the utilization capacity of its amino acids. As for carbohydrates, lactose, the only sugar present in human milk, should be the predominant carbohydrate, given its capacity for enhancing the absorption of calcium and promoting more physiological intestinal flora. However, the presence of lactose curtails use in patients with intolerance associated with this sugar, and means that it is probably contaminated with intact CMPs. Dextrinomaltose and hydrolyzates of corn starch and modified corn starch are also used. The composition in fact should provide a pattern of fatty acids as similar as possible to that found in human milk, especially for vegetable oils.
3. Clinical trials of therapeutic effectiveness: the residual allergenicity of a CMP hydrolyzate should be tested with a challenge in vitro with preexisting IgE antibodies from sera of patients with immediate CMP allergy (RAST, RAST inhibition) or with prick tests in sensitized subjects (119), although a positive RAST or prick test for a hydrolyzate does not correlate with its possible clinical reactivity (120).
The definitive clinical method for evaluating the degree of allergenicity of hydrolyzates is controlled oral food challenge in patients with CMP allergy. It is considered that a formula is hypoallergenic when, in a controlled food challenge in a group of patients allergic to the native protein, 90% of patients tolerate the formula without presenting symptoms (confidence interval of 95%) (121). This recommendation, established by the Subcommittee on Nutrition of the American Academy of Pediatrics (122) and accepted by ESPACI (63) and ESPGAN (118), is based from the clinical point of view on a single study presented in 1989 (123) and published in 1991 (124), performed in older children with mainly chronic symptoms such as atopic dermatitis and asthma in addition to their CMP allergy. It is doubtful whether tolerance values can be established regardless of the type of patients included in the studies, since the situation may be different when the study is performed in infants with acute clinical manifestations of immediate hypersensitivity (the most frequent) (55) or when patients with non-IgE mediated CMP intolerance are included (125). At present, there is no method for predicting with absolute confidence that no infant will react adversely to a hypoallergenic formula.
4. Clinical trials of preventive effectiveness: extensive and partial hydrolyzates have been used in a range of studies on the prevention of allergopathies, with conflicting results (reviewed in 126). The current criterion (63) is that partial hydrolyzates are not recommended for prevention programs of allergic illnesses, whereas extensive hydrolyzates may be of some use, although their administration is not without problems.
To ensure the preventive effectiveness of a hydrolyzed formula, it is recommended that it should be administered to groups of infants with a family history of atopy (both parents, or a parent and a sibling) for at least 6 months, under controlled and randomized conditions (121). These children should be followed up for at least 1 year, or until the age of 18 months, and there should be a statistically significant reduction in the prevalence of allergic illnesses, clearly defined according to an accepted scale, in relation to the control group.
Elemental formulas based on amino acids or monomers
The nitrogen source of these formulas is constituted solely of synthetic amino acids. They are mixtures of essential and nonessential amino acids, with a profile based on human milk, containing vegetable fats (some in the form of MCT), dehydrated glucose syrup, no lactose, and supplemented with vitamins and trace elements (table XI). Minimal digestion is required to absorb them. Their disadvantages are high osmolarity, unpleasant taste and high cost; from a nutritional point of view, they have a worse nitrogen absorption than hydrolyzed formulas (127). Some studies show satisfactory results as regards stimulation and maintenance of growth, which were even better than with hydrolyzates (128), although the few data available are in need of confirmation.
| Table XI | ||||
| Elementary formulas | ||||
| BRAND NAME (Laboratory) | DAMIRA ELEMENTAL | NEOCATE | NUTRI 2000 JUNIOR | |
| CHARACTERISTICS | (Novartis Nutrition) | (SHS) | (Nutricia) | |
| Energy value (Kcal/100 mL) | 80 | 71.3 | 65 | |
| PROTEINS (g/100 mL) | 2.4 | 1.95 | 1.8 | |
| % calories | 12 | 10.9 | 8.8 | |
| Protein source | Amino acids | Amino acids | Amino acids | |
| Free AA/peptides | 100% Free AA | 100% Free AA | 100% Free AA | |
| Taurine | yes | yes | yes | |
| CARBOHYDRATE (g/100 mL) | 13 | 8.1 | 7.1 | |
| % calories | 63 | 45.4 | 44.1 | |
| Carbohydrate source | Dextrinomaltose 73% | Glucose 100% | Dextrinomaltose 100% | |
| Modified starch 27% | ||||
| LIPIDS (g/100 mL) | 2.4 | 3.45 | 3.4 | |
| % calories | 25 | 43.5 | 47.1 | |
| Fat source | MCT 68% | LCT 65% / MCT 35% | Vegetable fat 100% | |
| Vegetable fat (soy) 32% | Vegetable fat 100% | |||
| 55% safflower oil | ||||
| 30% coconut | ||||
| 15% soy | ||||
| *6/*3 Linoleic acid/Linolenic acid | 9.2 | 10 | 5 | |
| Carnitine | yes | yes | yes | |
| Iron (mg/100 mL) | 1 | 1.05 | 0.51 | |
| Ca/P | 1.2 | 1.4 | 2 | |
| Ca (mg/100 mL) | 97 | 48.75 | 54 | |
| P (mg/100 mL) | 80 | 34.5 | 27 | |
| Osmolarity (mOsm/L) | 248 | |||
| Osmolality (mOsm/g H2O) | 360 | 353 | 274 | |
| Presentation | 48.5 g sachets | 400 g tin | 500 g tin | |
| May 1998 (Information provided by the manufacturers). | ||||
The main indications of these formulas are for patients with CMP allergy and intolerance who do not tolerate alternative formulas of hydrolyzates and soy. They are also useful in cases of multiple food allergy or intolerance (109). Finally, they may also be indicated for gastrointestinal alterations due to elementary diet, such as the short intestine syndrome after intestinal resection, intestinal fistula or severe refractory diar-rhea in the infant. They should always be administered under strict supervision by a specialist.
FINAL CONSIDERATIONS
There are two groups of adverse reactions to CMP: (1) reactions of known immunological mechanism, among which only IgE-mediated immediate allergy to CMP has been accurately identified, and (2) reactions of CMP intolerance, whose mechanism of production is not completely clear, although a non-IgE-mediated immunological pathogeny has not been ruled out. Both groups of entities possess pathogenic, clinical, diagnostic and developmental characteristics of their own, which required different preventive and therapeutic
approaches.
1. The symptomatology of immediate CMP allergy corresponds to the typical characteristics of reactions of immediate hypersensitivity (acute cutaneous and digestive manifestations, anaphylaxis); atopic dermatitis or asthma may also occur, al-though their etiologic role must be carefully verified. In CMP intolerance the principal symptom is diarrhea, of generally progressive onset and with growing repercussions for the nutritional state of the patient. Some cases present lesions of the duodenojejunal mucosa, of a non specific nature (CMP-induced enteropathy); in other cases rectocolic involvement predominates (allergic or eosinophilic infantile colitis), with diarrhea with mucus and blood or rectorraghy, ulcerations, and an infiltrate of mucosal, eosinophils.
2. Among the factors that can favor the appearance of immediate CMP allergy, one of the most important is early contact with minimal, repeated doses of CMP, e.g. the passage of CMP through mother''s milk, or sporadic contact, such as occasional bottles given to newborns. Nonetheless, these factors are not sufficient in themselves, since a genetic predisposition consisting of a high capacity to generate IgE response is fundamental ("atopic risk" subjects). Risk factors for CMP intolerance have not been identified, although it is frequent to find a history of acute gastroenteritis and early artificial feeding. Atopic children, or children with atopic risk, have not been shown to have a higher predisposition than other children towards CMP intolerance.
3. Diagnosis of immediate CMP allergy is based on suggestive clinical history, the presence of CMP-specific IgE (prick test or in serum) and verification of the relation between the symptoms and the intake of cow''s milk, via controlled food challenge, which should be performed in all cases except those in which the evidence, or the danger of the procedure, do not justify it. No laboratory parameters can be applied to the diagnosis of CMP intolerance, which is based solely on clinical criteria via
elimination and reexposure to cow''s milk. Duodenojejunal biopsy is only rarely used, due to its lack of correlation with the clinical manifestations. Rectosigmoidoscopy, together with the evaluation of several biopsy samples, may be useful in severe cases of colitis and in patients who do not improve with the elimination diet.
4. Once diagnosis of immediate CMP allergy is established, the only really effective treatment is a strict CMP-free diet, since even small quantities may favor the persistence of or increase in sensitization even in the absence of symptoms. As substitutes, formulas with a different source of intact protein, such as soy, and extensively hydrolyzed CMP formulas are used. If these formulas are not tolerated, elementary amino acid formulas are used. Partially hydrolyzed formulas should never be used to treat CMP allergy, since a portion of their proteins are intact and there fore still allergenic.
There are no data on how strict an elimination diet should be in CMP intolerance. Soy derivatives are not recommended, because children with enteropathy may present intolerance to soy as well. The treatment of choice is based on formulas of extensive CMP hydrolyzates. There are no data on the possible effectiveness of partial hydrolyzates.
5. The prognosis of immediate CMP allergy is in general favorable; most cases remit before 3 years of evolution, although when they affain tolerance, many patients are still positive in prick tests for detectable specific IgE in serum. However, some patients may reach adulthood without being able to tolerate CMP. CMP allergy may also be the indicator of future sensitization to other foods or inhalants. In contrast, CMP intolerance is a self-limiting process, and under a CMP-free diet both the clinical manifestations and anatomical lesions, if there are any, tend to remit in a few months, and in practically all cases before the age of 2 years.
6. An analysis of these characteristics suggests that these processes should not be considered as a single entity or a group of similar entities. A clear distinction should be made and individual cases treated on their own merits in order to avoid an atmosphere of confusion which may affect diagnostic, therapeutic and prognostic approaches.
Correspondence:
M. Martín Esteban
Hospital Infantil "La Paz"
Paseo de la Castellana, 261
28046 Madrid
ACKNOWLEDGEMENTS
We thank Laboratorio Milupa, S. A., for the financial contribution to the English translation.
REFERENCES
1. Bruijnzeel-Koomen C, Ortolani C, Aas K. et al. Adverse reactions to food (position paper). Allergy 1995;50:623-35.
2. Høst A. Cow''s milk protein allergy and intolerance in infancy. Some clinical, epidemiological and immunological aspects. Pediatr Allergy Immunol 19945;5(suppl 5):5-36.
3. Crespo JF, Pascual C, Burks AW, Helm RM, Esteban MM. Frequency of food allergy in a pediatric population from Spain. Pediatr Allergy Immunol 1995;6:39-43.
4. Blumenthal MN, Yunis E, Mendell N, Elston RC. Preventive allergy: genetics of IgE mediated diseases. J Allergy Clin Immunol 1986;78:962-8.
5. Hattevig G, Kjellman B, Johansson SGO, Björksten B. Clinical symptoms and IgE responses to common food proteins in atopic and healthy children. Clin Allergy 1984;14:551-9.
6. Hattevig G, Kjellman B, Björksten B. Clinical symptoms and IgE responses to common food proteins and inhalants in the first 7 years of life. Clin Allergy 1987;17:571-8.
7. Høst A. Adverse reactions to foods: epidemiology and risk factors. Pediatr Allergy Immunol 1995;6(suppl 8):20-8.
8. Fälth-Magnusson K, Kjellman NIM. Development of atopic disease in babies whose mothers were on exclusion diet during pregnancy. A randomized study. J Allergy Clin Immunol 1987;80:868-75.
9. Aas K. Chemistry of food allergens. In: Businco L, Oehling A, Renner B, Moran J, eds. Food allergy in infancy. Madrid: Garsi SA; 1992:9-20.
10. Yunginger JW. Food antigens. In: Metcalfe DD, Sampson HA, Simon RA, eds. Food allergy. Adverse reactions to foods and food additives. Oxford: Blackwell Science; 1997:49-63.
11. Ball G, Shelton MJ, Walsh BJ, Hill DJ, Hosking CS, Howden ME. A major continuous allergenic epitope of bovine betalactoglobulin recognized by human IgE binding. Clin Exp Allergy 1994;24:758-64.
12. Kohno Y, Honma K, Saito K, et al. Preferential recognition of primary protein structures of alpha-casein by IgG and IgE antibodies of patients with milk allergy. Ann Allergy 1994;73: 419-22.
13. Dean TP, Adler BR, Ruge F, Warner JO. In vitro allergenicity of cow''s milk substitutes. Clin Exp Allergy 1993;23:205-210.
14. Savilahti E, Kuitunen M. Allergenicity of cow milk proteins. J Pediatr 1992;121:S12-S20.
15. Werfel S, Cooke S, Sampson HA. Clinical reactivity to beef in cow milk allergy children. J Allergy Clin Immunol 1992; 89:228-32.
16. Høst A, Samuelson EG. Allergic reactions to raw, pasteurized and homogenized/pasteurized cow milk: a comparison. Allergy 1988;43:113-8.
17. Jarret EE, Hall E. The development of IgE-suppressive immunocompetence in young animals. Influence of exposure to antigen in the presence and absence of maternal immunity. Immunology 1984;53:365-73.
18. DeKruyff RH, Fang Y, Umetsu DT. IL-4 synthesis by in vivo primed keyhole limpet hemocyanin-specific CD+ T cells. I. Influence of antigen concentration and antigen-presenting cell type. J Immunol 1992;149:3468-76.
19. Strobel S. Development of oral tolerance. In: Weck AL, Sampson H, eds. Intestinal immunology and food allergy. Nueva York: Raven Press; 1995:155-68.
20. Høst A, Husby S, Gjesing B, Larsen JN, Löwenstein H. Prospective estimation of IgG, IgG subclass and IgE antibodies to dietary proteins in infants with cow milk allergy. Levels of antibodies to whole milk protein, BLG and ovoalbumin in relation to repeated milk challenge and clinical course of cow milk allergy. Allergy 1992;47:218-29.
21. Jacobsen HP, Halken S, Høst A, Bender L. IgE-specific antibodies against cow''s milk protein in cord blood from newborns with and without atopic predisposition. Pediatr Allergy Immunol 1995;6(suppl 8):98. (Abstract).
22. Lilja G, Dannaeus A. Fälth-Magnusson K, et al. Immune response of the atopic woman and foetus; effects of high- and low-dose food allergen intake during late pregnancy. Clin Allergy 1988;18:131-42.
23. Kondo N, Kobayashi Y, Shinoda S, et al. Cord blood lymphocyte responses to food antigens for the prediction of allergic disorders. Arch Dis Child 1992;67:1003-7.
24. Piccinni MP, Mecacci F, Sampognaro S, et al. Aeroallergen sensitization can occur during fetal life. Int Arch Allergy Immunol 1993;102:301-3.
25. Kilshaw PJ, Cant AJ. The passage of maternal dietary proteins into human breast milk. Int Arch Allergy Appl Immunol 1984;75:8-15.
26. Høst A, Husby S, Hansen LK, Østerballe O. Bovine beta-lactoglobulin in human milk from atopic and non atopic mothers. Relationship to maternal intake of homogenized and unhomogenized milk. Clin Exp Allergy 1990;20:383-7.
27. Marsh DG. Allergens and the genetics of allergy. In: Sela M, ed. The antigens. New York: Academic Press, 1975; III:271-359.
28. Martín Esteban M. Alimentación y alergia. In: Polanco I, ed. Nutrición profiláctica y terapéutica. Madrid: Saned; 1991:95-112.
29. Ghisolfi J, Olives JP, Le Tallec C, Cohen J, Ser N. Alimentation lactée du nourrisson et allergie aux proteines du lait de vache. Arch Pediatr 1995;2:526-31.
30. Martín Esteban M, Pascual Marcos C, García Ara MC, Ojeda Casas JA. Influencia de la lactancia en la aparición de alergia inmediata a proteínas de leche de vaca. Rev Esp Allergol Immunol Clin 1986;1:63-7.
31. Martín Esteban M, Pascual Marcos C. Alergia a alimentos. Medicina, Tratado de Medicina Interna (5ª ed) 1991;80: 3109-20.
32. Ford RP, Hill DJ, Hosking CS. Cow''s milk hypersensitivity: immediate and delayed onset clinical patterns. Arch Dis Child 1983;58:856-62.
33. Hill DJ, Firer MA, Shelton MJ, Hosking CS. Manifestation of milk allergy in infancy: clinical and immunological findings. J Pediatr 1986;109:270-6.
34. Martín Esteban M, Polanco I, Ojeda JA, Laso MT, Díaz Pena JM, Vázquez C. Correlaciones clínica-immunológicas en la intolerancia a proteínas de vaca en el niño. Allergol Immunopathol 1980;suppl 7:387-9.
35. Høst A. Halken S. A prospective study of cow milk allergy in Danish infants during the first three years of life. Clinical course in relation to clinical and immunological type of hypersensitivity reaction. Allergy 1990;45:587-96.
36. Sampson HA. Eczema and food hypersensitivity. In: Metcalfe DD, Sampson HA, Simon RA, eds. Food allergy: adverse reactions to foods and food additives. Oxford: Blacwell Science; 1997:193-209.
37. Pearson DJ. Clinical diagnosis in food allergy. Clin Exp Allergy 1989;19:83-5.
38. Martín Esteban M, Pascual Marcos C, Díaz Pena JM, Ojeda Casas JA. Alergia alimentaria. In: Sociedad Española de Alergología e Immunología Clínica, ed. Tratado de Alergología e Immunología Clínica, Tomo VI. Madrid: Luzan 5 SA; 1989:57-91.
39. May CD. Objective clinical and laboratory studies of immediate hypersensitivity reactions to foods in asthmatic children. J Allergy Clin Immunol 1976;58:500-15.
40. Yunginger JW. Lethal food allergy in children. N Engl J Med 1992;327:421-2.
41. Finkelstein H. Kuhmilch als Ursach Akuter Ernahrungsstoerungen beir Sauglingen. Monatssch Kinderheilk 1905;4:65-72.
42. Frankland AW. Anaphylaxis in relation to food allergy. In: Brostoff J, Challacombe SJ, eds. Food allergy and intolerance. Londres: Baillière Tindall, 1989:456-66.
43. García Ara MC, Boyano Martínez T, Martín Esteban M, Martín Muñoz F, Díaz Pena JM, Ojeda Casas JA. Actitud terapéutica y pronóstico en la alergia a alimentos. Allergol Immunopatol 1996;24(suppl 1):31-5.
44. Dordal MT. Leches alternativas en alergia a proteínas de leche de vaca. In: Lleonart R, Gaig P, Marquès Ll, Guspi R eds. Manual de Alergología. Barcelona: Masson-Salvat; 1995:237-44.
45. Bernstein IL, Storms WW. Practice parameters for allergy diagnostic testing. Ann Allergy 1995;75(6 part 2):554-60.
46. Høst A, Jacobsen HP, Halken S, Holmenlund D. The natural history of cow''s milk protein allergy/intolerance. Eur J Clin Nutr 1995;49(suppl 1):S13-S18.
47. Isolauri E, Turjanmaa K. Combined skin prick test and patch testing enhances identification of food allergy in infants with atopic dermatitis. J Allergy Clin Immunol 1996;97:9-15.
48. Sampson HA, Ho DG. Relationship between food-IgE-specific concentrations and the risk of positive food challenges in children and adolescents. J Allergy Clin Immunol 1997;100: 444-51.
49. James JM, Sampson HA. Immunologic changes associated with the development of tolerance in children with cow milk allergy. J Pediatr 1992;121:371-7.
50. May CD, Fomon SJ, Remigio L. Immunologic consequences of feeding infants with cow''s milk and soy products. Acta Paediatr Scand 1982;71:43-51.
51. Kondo N, Fukutomi O, Agata H, et al. The role of T lymphocytes in patients with food-sensitive atopic dermatitis. J Allergy Clin Immunol 1993;91:658-68.
52. Hill DJ., Ball G., Hoskings CS. Clinical manifestations of cow''s milk allergy in childhood. I: Association with in vitro cellular immune responses. Clin Allergy 1988;18:469-79.
53. Agata H, Kondo N, Fukutomi O, Shinoda S, Orii T. Interleukin-2 production of lymphocytes in food sensitive atopic dermatitis. Arch Dis Child 1992;67:280-4.
54. Sampson HA, Albergo R. Comparision of results of skin tests, RAST, and double-blind, placebo-controlled food challenges in children with atopic dermatitis. J Allergy Clin Immunol 1984;74:26-30.
55. Martín Esteban M, García Ara MC, Banque Molas M, Boyano Martínez MT, Martín Muñoz F, Díaz Pena JM. Evaluation of an extensively hydrolyzed casein-whey protein formula in immediate cow''s milk protein hypersensitivity. J Ped Gastroenterol Nutr 1998;26:398-401.
56. Baehler P, Chad Z, Gurbindo C, Bonin AP, Bouthillier L, Seidman EG. Distinct patterns of cows milk allergy in infancy defined by prolonged, two-stage double-blind, placebo-controlled food challenges. Clin Exp Allergy 1996;26:254-61.
57. Kjellman NIM. Adverse reactions to foods: management and prognosis. Pediatr Allergy Immunol 1995;6(suppl 8):54-8.
58. Businco L, Bruno G, Giampietro PG, Cantani A. Allergenicity and nutritional adequacy of soy protein formulas. J Pediatr 1992;121:S21-S28.
59. Bruno G, Giampietro PG, Del Guercio MJ, et al. Soy allergy is not common in atopic children: a multicenter study. Pediatr Allergy Immunol 1997;8:190-3.
60. Lifschitz CH, Hawkins HK, Guerra C, Byrd N. Anaphylactic shock due to cow''s milk protein hypersensitivity in a breast-fed infant. J Pediat Gastroenterol Nutr 1988;7:141-4.
61. Businco L, Cantani A, Longhi A, Giampietro PG. Anaphylactic reactions to a cow''s milk whey protein hydrolysate (Alfa-Re, Nestle) in infants with cow''s milk allergy. Ann Allergy 1989;62:333-5.
62. Saylor JD, Bahna SL. Anaphylaxis to casein hydrolysate formula. J Pediat 1991;118:71-4.
63. Businco L, Dreborg S, Einarsson R, et al. Hydrolysed cow''s milk formulae. Allergenicity and use in treatment and prevention. An ESPACI position paper. Pediatr Allergy Immunol 1993;4:101-11.
64. Businco L, Falconieri P, Giampietro PG, Bruno G. Prophylaxis of cow''s milk allergy. Monographs in Allergy 1996;32: 30-5.
65. Ragno V, Giampietro PG, Bruno G, Businco L. Allergenicity of milk protein hydrolysate formulae in children with cow´s milk allergy. Eur J Pediatr 1993;152:760-2.
66. Zeiger RS. Secondary prevention of allergic disease: an adjunct to primary prevention. Pediatr Allergy Immunol 1995; 6:127-38.
67. Croner S. Prediction and detection of allergy development: Influence of genetic and environmental factors. J Pediatr 1992;121:S58-S63.
68. Bjerke T, Hedegaard M, Henriksen TB, Nielsen BW, Schiøtz PO. Several genetic and environmental factors influence cord blood IgE concentration. Pediatr Allergy Immunol 1994; 5:88-94.
69. Kjellman NIM, Croner S, Fälth-Magnusson K, Odelram H, Björksten B. Predicción de alergia en la infancia. Allergy Proc (ed esp) 1992;1:43-8.
70. Rivas MA, Bone J, Riterto B, Alonso JP, Franco Y, Guallar A, Baldellou A. Cord blood IgE versus family history as atopic predictors in the newborn. Acta Pædiatr 1994;83:1308-9.
71. Kjellman NIM. Food allergy - Epidemiology and prediction. In: Harms HK, Wahn U, eds. Food allergy in infancy and childhood. Berlin: Springer-Verlag; 1989:205-7.
72. Hansen LG. How we define the high-risk groups for development of allergic disease? Pediatr Allergy Immunol 1996; 7(suppl 9):95-7.
73. European Allergy White Paper. Allergic diseases as a public health problem. Bruselas: The UCB Institute of Allergy, 1997:62.
74. Halken S, Høst A. Prevention of allergic disease. Exposure to food allergens and dietetic intervention. Pediatr Allergy Immunol 1996;7(suppl 9):102-7.
75. Fälth-Magnusson K. Dietary restrictions during pregnancy. In: de Weck AL, Sampson HA, eds. Intestinal Immunology and Food Allergy. Nueva York: Raven Press; 1995:191-201.
76. Zeiger RS. Breast-feeding and dietary avoidance. In: De Weck AL, Sampson HA, eds. Intestinal Immunology and Food Allergy. Nueva York: Raven Press; 1995:203-22.
77. Zeiger RS, Heller S. The development and prediction of atopy in high-risk children: Follow-up at age seven years in a prospective randomized study of combined maternal and infant food allergen avoidance. J Allergy Clin Immunol 1995; 95:1179-90.
78. Saarinen UM, Kajosaari M. Breastfeeding as prophylaxis against atopic disease: prospective follow-up study until 17 years old. Lancet 1995;346:1065-9.
79. Björksten B, Kjellman NIM. Does breast-feeding prevent food allergy? Allergy Proc 1991;12:233-7.
80. Björksten B. Immunological interaction between the mother and her infant in relation to the development of food allergy. Monographs in Allergy 1996;32:16-24.
81. Hide DW. Early intervention for the prevention of atopic dermatitis. Pediatr Allergy Immunol 1997;8:7-10.
82. Oldæus G, Anjou K, Björksten B, Moran JR, Kjellman NIM. Extensively and partially hydrolysed infant formulas for allergy prophylaxis. Arch Dis Child 1997;77:1-10.
83. Chandra RK, Puri S, Hamed H. Influence of maternal diet during lactation and use of formula feeds on development of atopic eczema in high risk infants. Br Med J 1989;299:228-30.
84. Halken S, Høst A, Hansen LG, Østerballe O. Preventive effect of feeding high-risk infants a casein hydrolysate formula or an ultrafiltrated whey hydrolysate formula. A prospective, randomized, comparative clinical study. Pediatr Allergy Immunol 1993;4:173-81.
85. MacDonald TT, Spencer J. Evidence that activated mucosal T cells play a role in the pathogenesis of enteropathy in human small intestine. J Exp Med 1988;167:1341-9.
86. Schmitz J, Rey F, Jos J, Rey J. Sensibilisation aux proteines du lait et du soja. Arch Franç Ped 1976;33:719-21.
87. Iyngkaran N, Abidin Z, Meng LL, Yadav M. Egg-protein induced villous atrophy. J Ped Gartroenterol Nutr 1982;1:29-33.
88. Vitoria JC, Camarero C, Sojo A, Ruiz A, Rodríguez Soriano J. Enteropathy related to fish, rice and chicken. Arch Dis Child 1982;57:44-8.
89. Cavataio F, Carroccio A, Montalto G, Iacono G. Isolated rice intolerance: clinical and immunological findings in four infants. J Pediatr 1996;128:558-60.
90. Iacono G, Carroccio A,. Cavataio F, et al. Gastroesophageal reflux and cow''s milk allergy in infants: a prospective study. J Allergy Clin Immunol 1996;97:822-7.
91. Walker-Smith JA, Harrison M, Kilby A, Phillips A, France NE. Cow''s milk sensitive enteropathy. Arch Dis Child 1978;53: 375-80.
92. Vitoria JC, Sojo A, Rodríguez Soriano J. Changing pattern of cow''s milk protein intolerance. Acta Ped Scand 1990;79: 566-7.
93. Nagata S, Yamashiro Y, Ohtsuka Y, et al. Quantitative analysis and immunohistochemical studies on small intestinal mucosa of food-sensitive enteropathy. J Pediatr Gastroenterol Nutr 1995;20:44-8.
94. Gryboski JD, Burkle F, Hillman R. Milk-induced colitis in an infant. Pediatrics 1966;38:299-302.
95. Armisen A, Sancho B, Almaraz E, Prieto G, Polanco I. Colitis inducida por alergeno alimentario. Presentación de 20 cases. An Esp Pediatr 1996;44:21-4.
96. Goldman H, Proujanski R. Allergic proctitis and gastroenteritis in children. Clinical and mucosal biopsy features in 53 cases. Am J Surg Pathol 1986;10:75-86.
97. Lake AM, Whitington PF, Hamilton SR. Dietary protein-induced colitis in breast-fed infants. J Pediatr 1982;101:906-10.
98. Odze RD, Bines J, Leichtner AM, Goldman H, Antonioli DA. Allergic proctocolitis in infants: a prospective clinical-pathologic biopsy study. Hum Pathol 1993;24:668-74.
99. Vitoria JC, Camarero C, Solaguren R, et al. Cow''s milk protein sensitive enteropathy. Clinical and histological results of the cow''s milk provocation test. Helv Paediatr Acta 1979; 34:309-18.
100. Walker-Smith JA. Cow''s milk intolerance as a cause of postenteritis diarrhoea. J Pediat Gastroenterol Nutr 1982;1:163-73.
101. Martín Esteban M, Polanco I, Ojeda JA, Laso MT, Díaz Pena JM, Vázquez C. Correlaciones clínico-immunológicas en la intolerancia a proteínas de leche de vaca en el niño. Allergol Immunopathol 1980;suppl 7:387-9.
102. Martín Esteban M, Díaz Pena JM, Pascual C, Ojeda JA. Aspectos clínicos de la alergia a proteínas de leche de vaca. Rev Esp Allergol Immunol Clin 1990;5(suppl 3):13 (Abstract).
103. Chong SKF, Blackshaw AJ, Morson BC, Williams CB, Walker-Smith JA. Prospective study of colitis in infancy and early childhood. J Ped Gastroenterol Nutr 1986;5:352-8.
104. Vitoria JC, Sebastián MJ, Astigarraga I, Ariceta G, Sojo A, Rodríguez Soriano J. Intolerancia a proteínas de leche de vaca. Estudio epidemiológico. An Esp Pediatr 1989;31:261-4.
105. Sánchez T, González C, Hawkins F, Martín Esteban M, Quero J. Enterocolitis necrotizante asociada a intolerancia a proteínas de leche de vaca: A propósito de un caso. An Esp Pediatr 1997;46:611-2.
106. Glassman MS, Newman LJ, Berezin S, Gryboski JD. Cow milk protein sensitivity during infancy in patients with inflammatory bowel disease. Am J Gastroenterol 1990;85: 838-40.
107. Walker-Smith JA. Cow milk-sensitive enteropathy: predisposing factors and treatment. J Pediatr 1992;121:S111-S115.
108. Kelso JM, Sampson HA. Food protein-induced enterocolitis to casein hydrolysate formulas. J Allergy Clin Immunol 1993;92:909-10.
109. Hill DJ, Cameron DJS, Francis DEM, González-Andaya AM, Hosking CS. Challenge confirmation of late-onset reactions to extensively hydrolyzed formulas in infants with multiple food protein intolerance. J Allergy Clin Immunol 1995;96: 386-94.
110. Cantani A, Lucentini P. Natural history of soy allergy and/or intolerance in children, and clinical use of soy-protein formulas. Pediatr Allergy Immunol 1997;8:59-74.
111. Young VR. Soy protein in relation to human protein and amino acid nutrition. J Am Diet Assoc 1991;91:828-35.
112. ESPGAN, Committee on Nutrition. Comment on the composition of soy protein based infant and follow up formulas. Acta Paediatr Scand 1990;79:1001-5.
113. Lee YH. Food processing approaches to altering allergenic potential of milk-based formula. J Pediatr 1992;121:S47-S50.
114. Oldæus G, Björksten B, Einarsson R, Kjellman NIM. Antigenicity and allergenicity of cow milk hydrolysates intended for infant feeding. Pediatr Allergy Immunol 1991;2:156-64.
115. Wahn U. Role of hydrolysates in prophylactic and therapeutic diets for food allergy. In: De Weck AL, Sampson HA, eds. Intestinal Immunology and Food Allergy. Nueva York: Raven Press; 1995:289-94.
116. Mäkinen-Kiljunen S, Sorva R. Bovine-lactoglobulin levels in hydrolysed protein formulas for infant feeding. Clin Exp Allergy 1993;23:287-91.
117. Cordle CT, Duska-McEwen G, Janas LM, Malone WT, Hirsch MA. Evaluation of the immunogenicity of protein hydrolysate formulas using laboratory animal hyperimmunization. Pediatr Allergy Immunol 1994;5:14-9.
118. ESPGAN Committee on Nutrition, Aggett PJ, Haschke F, Heine W, et al. Comment on antigen-reduced infant formulae. Acta Paediatr 1993;82:314-9.
119. Wahn U, Wahl R, Rugo E. Comparison of the residual allergenic activity of six different hydrolyzed protein formulas. J Pediatr 1992;121:S80-S84.
120. Hoffman KM, Sampson HA. Serum specific-IgE antibodies to peptides in a casein hydrolysate formula. Pediatr Allergy Immunol 1997;8:185-9.
121. Kleinman RE. Cow milk allergy in infancy and hypoallergenic formulas. J Pediatr 1992;121:S116-S121.
122. American Academy of Pediatrics. Subcommittee on Nutrition and Allergic Disease. Infant formulas and allergic disease. 1990.
123. Sampson HA. Safety of casein hydrolysate formula in children with cow''s milk hypersensitivity (Abstract). Pediatr Res 1989;25(Suppl 4):123A.
124. Sampson HA, Bernhisel-Broadbent J, Yang E, Scanion SM. Safety of casein hydrolysate formula in children with cow milk allergy. J Pediatr 1991;118:520-5.
125. Halken S, Høst A, Hansen LG, Østerballe O. Safety of a new, ultrafiltrated whey hydrolysate formula in children with cow milk allergy: a clinical investigation. Pediatr Allergy Immunol 1993;4:53-9.
126. Martín Esteban M, Pascual C, García Ara MC. Prevención de la alergia alimentaria. Allergol Immunopathol 1998;26:93-7.
127. Tamayo G, Sáenz A, Hernández M, Pedrón C, García Novo MD. Fórmulas infantiles especiales. An Esp Pediatr 1997; 47:455-65.
128. Isolauri E, Sütas Y, Mäkinen-Kiljunen S, Oja SS, Turjanmaa K. Efficacy and safety of hydrolyzed cow milk and amino acid-derived formulas in infants with cow milk allergy. J Pediatr 1995;127:550-7.
