Comparison of the efficacy and safety of two preseasonal regimens of glutaraldehyde modified, tyrosine-adsorbed Parietaria pollen extract over a period of three years in monosensitive patients
J. M. Negro*, A. W. Wheeler, J. Hernández**, L. J. Youlten***. A. Pascual*, F. J. García-Sellés*, J. A. Pagán*, J. D. López-Sánchez*, J.C. Miralles*, F. Sarrió*, J. M. Milán*, L. G. Contreras and D. Vidal****
*Allergology Section. H. U. "Virgen de la Arrixaca". El Palmar. Murcia (Spain). **Bencard Allergy Unit. Beecham Pharmaceuticals. Epsom. Surrey (UK). ***Guys Hospital. London (UK). ****Química Farmacéutica Bayer. Barcelona (Spain).
Correspondence:
J. M. Negro-Álvarez
Residencial "La Paloma" A-1
El Palmar. 30120 Murcia. Spain
SUMMARY
The purpose of this study was to evaluate the clinical efficacy over a period of three years (1988-90) of two preseasonal dosage regimens of a Parietaria allergoid (Bencard Tyrosine Parietaria) in patients who were only sensitive to this pollen. Fifty patients were included (14 men and 36 women, age: mean, 28 years; range, 14-47 years). Twenty five patients (group A) were treated each january with the basic course of Bencard Tyrosine Parietaria. This consisted of injecting subcutaneously 0.5 ml from each of three vials, with one week between each injection. A further injection using the vial with the highest dose was given one week later. Each january and february, twenty five patients (group B) were treated with the basic course of Bencard Tyrosine Parietaria, repeating the last dose five times, with one week between each injection.
Immunotherapy with a tyrosine-adsorbed Parietaria judaica allergoid is an effective method for mitigating nasal (p < 0.0001), bronchial (p < 0.005), conjunctival (p < 0.001) and palatal itching symptoms (p < 0.0001) in patients who are sensitive to this pollen. Sensitivity to Parietaria pollen, as verified by skin test and nasal challenge, decreased during immunotherapy (p < 0.001). Histamine release by peripheral blood basophils decreased during the course of the study, falling from 43.5 ng/ml to 12.3 ng/ml in group A and from 42.9 ng/ml to 10.0 ng/ml in group B; during the second and third years, IgG levels were increased one and four months after starting treatment with the extract, while this was not the case after ten months; IgE levels were also increased. Finally, overall tolerance to this immunotherapy product was good in almost all patients.
Key words: Effectiveness. Histamine release. Immunotherapy. Safety. Specific IgE. Specific IgG.
RESUMEN
La finalidad de este estudio de tres años (1988-1990) fue comparar la eficacia clínica de dos regímenes de dosificación, administrados antes de la estación del polen, de un alergoide de Parietaria (Bencard Tyrosine Parietaria) en pacientes sensibles a este polen. Fueron incluidos 50 pacientes (14 varones y 36 mujeres; edad: media, 28 años; intervalo, 14-47 años). Veinticinco pacientes (grupo A) recibieron en enero de cada año un ciclo básico de Bencard Tyrosine Parietaria. Este tratamiento consistió en tres inyecciones subcutáneas, 0,5 ml de tres ampollas con dosis diferentes, administradas a intervalos de una semana entre inyección. Se administró una segunda inyección de la mayor dosis una semana más tarde. En enero y febrero de cada año, 25 pacientes (grupo B) recibieron un ciclo convencional de Bencard Tyrosine Parietaria de la última dosis administrada 5, con un intervalo de una semana entre inyecciones.
La inmunoterapia con un alergoide de Parietaria judaica de tirosina adsorbida es un método efectivo para aliviar los síntomas de irritación nasal (p < 0,0001), bronquial (p < 0,005), conjuntival (p < 0,001) y palatal (p < 0,0001) en pacientes sensibles al polen. La sensibilidad al polen de Parietaria, verificada mediante pruebas cutáneas y provocación nasal, disminuyó con la inmunoterapia (p < 0,001). La liberación de histamina por los basófilos de la sangre periférica disminuyó durante el estudio, de 45,5 ng/ml a 12,3 ng/ml en grupo A y de 42,9 ng/ml a 10,0 ng/ml en grupo B. En el segundo y tercer año, los niveles de IgG aumentaron un mes y cuatro meses después del comienzo del tratamiento con el extracto, pero no a los diez meses. Los niveles de IgE también aumentaron. Para concluir, la tolerancia general de esta inmunoterapia fue buena en casi todos los pacientes.
Palabras clave: Efectividad. Liberación de histamina. Inmunoterapia. Seguridad. IgG específica. IgE específica.
INTRODUCTION
Parieteria pollinosis is very common in the Mediterranean area (1-9). Although there is a predominance of Parietaria judaica, a certain degree of cross-reactivity with other Parietaria species occurrs (10, 11).
Since it was introduced by Freeman and Noon in 1911 (12, 13), allergen-specific hyposensitization, has been used frequently in allergic conditions, particularly in pollinosis, although it is now recommended that it must only be administered in certain patients (14-16). Controlled studies have shown that hyposensitization with pollen extracts is beneficial for patients (16), and there are some studies available of Parietaria extract versus placebo (17-24).
The purpose of this study was to evaluate the clinical efficacy over a period of three years of two preseasonal dosage regimens with a Parietaria allergoid in patients who were only sensitive to this pollen in order to optimise the dosage regime with this product which has previously been shown to be efficaceous. The guidelines of Aas (25) have been followed with regard to the proper performance of an immunotherapy clinical trial. The general principle that immunotherapy can be effective is accepted by many people, so the use of placebo groups is regarded now to be non-ethical.
METHODS
Patients
The patients were diagnosed as having rhinitis and/or bronchial asthma due to sensitization solely to Parietaria judaica, in accordance with the following criteria: background of seasonal symptoms consistent only with the period of Parietaria pollination (for two or more seasons), monosensitization to a Parietaria pollen extract (as shown by a skin prick test, RAST class 2 or greater, Histamine Release Test (HRT), or nasal challenge), no previous immunotherapy and no skin-test or history of allergy to grass pollens, olive tree pollen, home-dust mite, cat or dog.
50 patients fulfilling these criteria were included (14 men and 36 women, age: mean, 28 years; range, 14-47 years) after giving their written consent, having received beforehand information on their condition, treatment alternatives, risks and prognosis, as provided in Art. 10, para. 5, of the General Health Act (26). The study was performed in accordance with the guidelines of the Declarations of Helsinki and Tokyo (27, 28), after approval by our Hospital''s Research Committee.
The patients were randomized into two groups of 25 patients and allocated to one of the two treatment groups.
Routine laboratory tests (hematology and blood chemistry) were carried out in all the patients in order to rule out any possible concurrent diseases.
Clinical evaluation
Symptom and medication scores
The efficacy of the immunotherapy (IT) was assessed on the basis of a daily record of the symptoms kept for the three years that the study has lasted. All of the patients were provided with instructions for filling in diary cards in which the intensity of the ocular (itching, lacrimation, and reddening), nasal (itching, sneezing, obstruction and hydrorrhea), and bronchial (coughing, chest sounds, and dyspnea) symptoms were evaluated, allocating a score between zero and three depending on the severity of each symptom. The patients also recorded each day the brand name and doses of the drugs required to control any symptoms that did occur. The asthmatic patients performed three measurements in the morning and a further three measurements at night of the Maximum Expiratory Flow, using a mini Wright Peak Flow Meter. The diary cards were sent by the patient to the hospital Outpatients Department at the end of each month. Any patients not sending in their diary cards were reminded after two weeks. At the end of the period of Parietaria pollination, both the patient and the doctor carried out a subjective assessment of the former''s progress in accordance with the following scale of symptoms: 0 = Same as or worse than last year''s season, 1 = Slightly better than last year''s season, 2 = Better than last year''s season, 3 = Much better than last year''s season.
Pollen counts
The pollen was collected using a Burkard Spore Trap (Burkard Manufacturing Ltd., Rickmansworth, England), subsequently calculating the daily concentration of Parietaria pollen per cubic metre of air (29).
Extracts used for diagnosis
The Parietaria judaica pollen had been extracted to a concentration of 2.5% in 0.01M NH4HCO3 for 4 hours, filtered and freeze-dried and stored below 4° C. The same batch of material was used throughout in order to mantain consistency.
The freeze-dried extract was reconstituted to a concentration of 2.5% with phosphate buffer saline (PBS) and glycerol (46%) and stored at 4° C. Dilutions of extract were prepared at the time of use using phenolated PBS (0.05%).
Treatment
During three years, patients received a preseasonal therapy with a standardised (30, 31) glutaraldehyde-modified, tyrosine-adsorbed Parietaria judaica extract (Bencard Tyrosine Parietaria) as outpatients in the Hospital. In the case of asthmatic patients, 3 measurements of the MEF were performed immediately before giving the extract. If the result was less than 50% of the forecast value, the injections were not given. A further three measurements were performed 1 hour after giving the injection. All results were recorded on a tolerance form, also indicating, if they appeared, the local (severity, size, type and persistence) and systemic reactions, and the treatment given to control them.
Group A. Basic Course
The patients were treated each january with the basic course of Bencard, Smithkline Beecham (UK) Tyrosine Parietaria extract, supplied in Spain by Bayer. This consisted of injecting subcutaneously 0.5 ml from each of three vials (600 SU/ml, 1600 SU/ml, 4000 SU/ml) (30, 31), with one week between each injection. A further injection using the vial with the highest dose was given one week later. These patients received a total dose of 5.100 SU.
Group B. Basic Course plus Extension
Each january and february, the patients were treated with the basic course of Bencard Tyrosine Parietaria, repeating the last dose five times, with one week between each injection. The total dose received was 15.100 SU.
In vivo test
It was systematically verified that none of the patients were taking any type of interfering medication. Skin prick test and nasal challenge were carried out before giving the IT (january), at the end of the Basic Treatment (february), at the height of the Parietaria pollination season (may) and after the pollination season (november)
Prick Test
A prick test was performed in duplicate on the upper surface of the forearm in all patients, in accordance with the procedure described by Morrow Brown (32), and using Dome/Hollister Stier lancets, with nine dilutions of the extract (from 1/1 to 1/6561). 1% histamine was used as positive control and phenolated phosphate buffer saline (PPBS) solution as negative control. Readings were performed after 15 minutes, tracing the outline of the papule with a felt-tip pen, transferring the outline to tracing paper by pressing on the papule and then measuring the diameter. The test was considered to be positive when the maximum papule diameter measured 3 mm or more. In order to avoid circadian variations in the results of the tests, all of the tests were performed between 9 and 10 a.m.
Nasal challenge
A modification of the method described by Corrado et al (33) was used. The nasal challenge consisted of administering nasal sprays (Fisons) containing increasing concentrations of a Parietaria judaica extract, and measuring the variations in obstruction using a modification of the mini Peak Flow Meter, the Youlten PNIF Meter (Peak Nasal Inspiratory Flow) (C. Clarke), which determines nasal flow by means of a simple inspiratory manoeuvre. Before carrying out this test, it was verified that the baseline PNIF was greater than 100 l/min, by recording three measurements performed with 5 minutes between each one. Subsequently, the changes occurring after spraying the solvent (PPBS) in both nostrils were measured in order to evaluate non-specific nasal reactivity. One spray (0.13 ml) of PPBS was applied in each nostril, followed by increasing concentrations of Parietaria judaica, starting with the next highest concentration after that which, in the prick test, produced a maximum diameter exceeding 3 mm. The PNIF was measured 15 minutes after each dose, repeating the measurement twice more for each dose with 5 minutes between each measurement. The challenge was considered positive when the PNIF fell to 50% or less of the baseline flow, more than five sneezes appeared in the 5 minutes after giving the dose, or hydrorrhea exceeded 0.5 ml in the same period of time.
In vitro test
Blood samples were obtained from each patient for the laboratory tests at the times previously stated for in vivo tests (january, february and november). Each blood sample was divided into two tubes: one containing sodium heparin in which whole blood was used to carry out the Histamine Release Test (HRT) on the same day as extracted; the other tube, containing blood for the separation of serum, was aliquoted into 4 tubes, and stored frozen at -20° C until the other assays were carried out.
Assay of total and specific IgE
The total IgE assay was carried out using Phadebas IgE PRIST kits (Pharmacia Diagnostic AB, Uppsala, Sweden) having the same batch number. The IgE antibodies specific for Parietaria judaica were quantified using Phadezym-RAST kits (Pharmacia Diagnostic AB, Uppsala, Sweden) having the same batch number. All the assays were carried out in duplicate, using dilutions where necessary. The results of the specific IgE assays were expressed in Phadezym-RAST Units (PRU) in order to detect small differences that may not have been apparent using the conventional classes of Phadezym-RAST.
Assay of IgG antibodies
IgG antibodies specific for P. judaica were studied using a microplate technique. The microtitre plate wells were coated with 100 µl of a Parietaria pollen extract (100 µg/ml) dissolved in PBS (Difco) with 0.1% sodium azide at 4° C for 72 hours. After washing four times with PBS, 200 µl of 1% bovine serum albumin in PBS were added in each well. After incubating for 4 hours at 20° C, the plates were washed 4 times with PBS and incubated for 18 hours at 37° C with 50 µl of patient serum, Tween 20 (1%) and 0.1% sodium azide. Subsequently, the plates were washed 6 times with PBS and Tween 20 (1%). 50 µl of Staphylococcal Protein A (Pharmacia) (50 µl contain 10 ng of protein) labelled with I/125 (Amersham International plc) were added, in accordance with Hunter''s method (34), for 3 hours at 20° C, and then washed 6 times with PBS/Tween, after which the radioactivity was counted. The IgG levels were expressed as the quantity of Staphylococcal Protein A bound to IgG from the 10 µl of serum per well.
Histamine Release Test (HRT)
For quantifying the histamine released, the technique described by Shore (35) was followed, after incubating peripheral blood leukocytes with Parietaria pollen extract. This technique has been subsequently automated by other authors (36, 37) and further modifications have managed to reduce the cost of the process in time and reagents (38, 39), providing the possibility of using whole blood (40, 41) instead of isolated leukocytes, as in the original method (42), with similar results.
0.4 ml of peripheral blood obtained from each patient (collected in heparinized Venoject tubes) was incubated for 30 minutes at 37° C while stirring with 0.02 ml of the dilutions of Parietaria judaica. After adding 1.6 ml of 1.5 mM EDTA to each tube, the samples were centrifuged for 15 minutes at 1600 rpm. The supernatant was collected the histamine released was measured using a fluorimetric technique based on the reaction of the former with OPT (ortho-phthaldealdehyde) in a strongly alkaline medium, forming a fluorescent complex that can be measured using a Technicon AIP device. The HRT includes the assay of total and baseline histamine, and the histamine released after incubating with the various dilutions. All the assays were performed in duplicate and the results were calculated in accordance with the following formula:
The response to the allergen studied was considered to be positive when more than 20% of histamine was released. All the samples were checked beforehand for the ability to release mediators by incubating with anti-IgE.
Adverse effects
The local and systemic adverse effects were recorded in accordance with the criteria indicated in table I. In the event of obtaining local reactions scoring 2 or more, the dose was readjusted and the appropriate treatment was given. In the event of systemic reactions scoring 3, the patient was withdrawn from the study. Immediate reactions were considered to be those that occurred within 30 minutes after giving the dose and late reactions were those appearing after this time.
| Table IAdverse effects | |||||
| Local reactions | |||||
| Score 0 | Score 1 | Score 2 | Score 3 | ||
| Erythema and swelling up to 2 cm in diameter and/or mild local pain and/or mild local itching | Erythema and swelling with an area exceeding that of the palm of the hand and/or moderate local pain and/or moderate local itching | Erythema and swelling with an area exceeding that of the palm of the hand and/or severe local pain and/or severe local itching | Any reaction more severe than those of score 2 or local urticaria | ||
| Systemic reactions | |||||
| Score 1 | Score 2 | Score 3 | |||
| Mild rhinitis and/or conjunctivitis and/or itching, rash or urticaria not requiring treatment | More severe rhinitis and/or conjuctivitis and/or itching, rash or urticaria requiring and relieved by treatment | Symptoms as in score 2 but which are not relieved by treatment; also dyspnea, sibilant rales, palpitations, dizziness or loss of consciousness | |||
Statistical analysis
The between-group analysis was carried out using a variance analysis for a hierarchized factorial design. For the within-group comparison, the Student''s t test for paired data was used.
RESULTS
One female patient had to be withdrawn from the study due to a systemic reaction after giving the second dose of vial number 3, after having tolerated all the previous doses. Another female patient was excluded from the study because she left the country, two due to pregnancy, four for not filling in the forms correctly and five for not properly completing the follow-up period scheduled in the study. 37 patients (19 from group A and 18 from group B) completed the entire protocol.
Group homogeneity
Table II provides the baseline details of both groups.
Table II Group homogeneity | ||
| Group A | Group B | |
| No. Patients | 25 | 25 |
| Age | 26,52 ± 7,38 | 29,47 ± 9,64 |
| Positive Prick-Test Dilution | 2.721 ± 2.584 | 3.159 ± 2.357 |
| Positive Nasal Challenge Dilution | 56 ± 103 | 108 ± 174 |
| Specific IgE (PRU/ml) | 5,61 ± 4,02 | 6,36 ± 4,35 |
| Specific IgG | 0,453 ± 0,284 | 0,381 ± 0,362 |
Pollen counts
The mean parietaria pollen counts for each month throughout the study is represented in figure 1.
Figure 1.--Pollen counts (triangles) and nasal, conjunctival, palatal and asthma symptoms/medication score for the Basic Course (circles) and the Basic Course plus Extension (crosses) groups througout the study are shown, during the three years. Fe (february), Ma (may), No (november).
Clinical efficacy (symptoms/medication)
Figure 1 shows the daily mean of nasal, ocular, asthma and palatal symptoms/medication scores in the 37 patients (19 from group A and 18 from group B) who completed the symptoms diary cards.
Nasal symptoms/medication
A significant decrease in nasal symptoms was observed in both groups of patients (p < 0.0001) throughout the study from a daily mean score in the first year of 0.354 (0.330 in group A and 0.379 in group B) to 0.238 in the second year (0.244 in group A and 0.23 in group B) and 0.133 in the third year (0.116 and 0.151, respectively), even though there appeared to be little variation between annual pollen counts; there were no significant differences between the two treatment groups.
Significant season-related differences (p < 0.0001) were observed in the measurements performed over the three year period. Symptoms were most severe during may (daily mean: 0.364), moderate in february (mean: 0.261) and mildest in november (0.101).
Ocular symptoms/medication
These symptoms also decreased during the follow-up period in both groups of patients. In group A, the daily average (of all three measurements) decreased from 0.100 in the first and second year to 0.055 in the last year; in group B, it fell from 0.160 in the first year to 0.06 in the third year (p < 0.001). No significant differences were observed between the two groups. After adjusting for seasonal differences, in the study as a whole, symptoms were more severe in may (daily mean, 0.149) than in february (0.117), the difference between the two months fell just short of significance, while in both months symptoms were significantly more severe (p < 0.0001) than in november (0.030).
Asthma symptoms/medication
Bronchial symptoms were significantly less severe (p < 0.005) during the last year in both treatment groups, with a daily mean for the year as a whole of 0.002 in group A and 0.022 in group B, compared with the first year (0.028 in group A and 0.052 in group B) and 1989 (0.041 in group A and 0.044 in group B). The differences between the groups did not attain statistical significance. During the three-year period, the patients scored highest in may (0.056), followed by january-february (0.033) and finally october (0.005). The differences are statistically significant (p < 0.001).
Palatal itching/medication
The symptoms records show a greater degree of palatal itching (p < 0.0001) during the first year (daily mean of 0.109 in group A and 0.223 in group B) than during the second (0.075 and 0.148, respectively) and the third year (0.038 and 0.095, respectively); the differences between the groups were not statistically significant. By seasons, the symptoms were also more intense in the order may, january-february, october, with daily means of 0.173, 0.133 and 0.035, respectively, in the total patient population (p < 0.0001).
In vivo test
Skin tests
Over the course of the study, there was a significant increase in both groups of patients in the concentration of allergen required in the skin test to produce a papule equivalent to that of the histamine control (p < 0.001). In group A, this concentration had increased from an average dilution of 1/2721 at the start of the study to 1/21 at the end of the study; in group B, this concentration increased from 1/3159 to 1/42. There were no significant differences between the two groups (Fig. 2).
Figure 2.--Parietaria extract dilution required to produce a papule equivalent to histamine control for the Basic Course (A) and the Basic Course plus Extension (B) groups along the study. Fe (february), Ma (may), No (november).
Nasal challenge
Also in the course of the study (Fig. 3), there was a similar, and significant (p < 0.001), increase in the tolerance to the Parietaria judaica pollen given intranasally in the form of a challenge test. In group A, the mean dilutions decreased from 1/56 at the start of the study to 1/11 at the end of the study. In group B, the dilutions decreased from 1/108 to 1/22.
Fig. 3 Dilutions required to induce a positive nasal challenge for the Basic (A) and Basic plus Extension (B) groups along the study. Fe (february), Ma (may), No (november).
In vitro test
Specific IgE
The IgE counts increased in both treatment groups (p < 0.001), increasing in group A from 5.61 PRU/ml at the start of the study to 27.98 at the end of the study; in group B, the count increased from 6.36 at the beginning of the study to 29.54 at the end of the study (table III).
| Table IIIChanges in specific IgE (PRU/ml) during study | ||||||||||
| 1987 Nov. | Feb. | 1988 May. | Nov. | Feb. | 1988 May. | Nov. | Feb. | 1990 May. | Nov. | |
| Group A | 5.61 ± 4.02 | 7.37±4.97 | 8.86 ± 4.85 | 9.37 ± 3.99 | 14.91 ± 11.49 | 21.00 ± 33.00 | 15.83 ± 12.62 | 10.09 ± 2.85 | 47.67 ± 41.126 | 27.98 ± 27.40 |
| Grupo B | 6.36 ± 4.35 | 22.38 ± 65.75 | 24.17 ± 71.61 | 15.61 ± 38.82 | 17.78 ± 32.22 | 12.59 ± 9.53 | 55.51 ± 143.9 | 7.11 ± 4.53 | 9.30 ± 128.1 | 29.54 ± 40.45 |
Changes in specific IgG during study | ||||||||||
| 1987 Nov. | Feb. | 1988 May. | Nov. | Feb. | 1988 May. | Nov. | Feb. | 1990 May. | Nov. | |
| Group A | 0.45 ± 0.28 | 0.35 ± 0.14 | 0.27 ± 0.17 | 0.24 ± 0.14 | 0.55 ± 0.38 | 0.60 ± 0.39 | 0.34 ± 0.22 | 1.33 ± 0.75 | 1.19 ± 0.79 | 0.50 ± 0.18 |
| Group B | 0.38 ± 0.36 | 0.38 ± 0.20 | 0.20 ± 0.05 | 0.19 ± 7.90 | 0.44 ± 0.33 | 0.52 ± 0.18 | 0.31 ± 0.12 | 1.08 ± 0.50 | 1.05 ± 0.30 | 0.47 ± 0.15 |
IgG antibodies
The IgG counts decreased in both treatment groups during the first year of the study (p < 0.01) from 0.45 in group A and 0.38 in group B to 0.24 and 0.19, respectively ( III). However, during the next two years, these values increased during february and may, falling back in november of both years to levels similar to those obtained at the start of the study. There were significant differences from baseline levels in the assays performed in may of the second year (p < 0.05), obtaining 0.61 in group A and 0.52 in group B; in february of the third year (p < 0.001), with 1.33 in group A and 1.08 in group B; and in may of the same year (p < 0.001), obtaining 1.19 and 1.05 in groups A and B, respectively.
Histamine release
The histamine released by peripheral blood basophils decreased significantly in both groups after incubation with Parietaria judaica, falling from 43.5 ng/ml to 12.3 ng/ml in group A and from 42.9 ng/ml to 10.0 ng/ml in group B at the end of the study (Fig. 4). There were no significant differences between the two groups.
Fig. 4 Percentage of histamine released by peripheral blood basophils in the Basic (A) and the Basic plus Extension (B) groups after incubation with Parietaria along the study. Fe (february), Ma (may), No (november).
Adverse reactions
One female patient was excluded from the study in the first year after suffering an asthma attack 60 minutes after being given the second dose of vial no. 3, although she had tolerated the previous doses. There were 125 (15.54%) local reactions to the 804 injections given (table IV). However, after readjusting the dose, they were not so severe as to prevent completion of treatment.
Table IVAdverse local reactions | ||||
| 1988 | 1989 | 1990 | Total | |
| Vial 1 | ||||
| Score 1 | 6 | 7 | 8 | 21 |
| Score 2 | 2 | 5 | 7 | 14 |
| Score 3 | 1 | 0 | 0 | 1 |
| Total injections given | 51 | 44 | 44 | 139 |
| Vial 2 | ||||
| Score 1 | 3 | 7 | 10 | 20 |
| Score 2 | 8 | 3 | 3 | 14 |
| Score 3 | 0 | 0 | 0 | 0 |
| Total injections given | 59 | 40 | 38 | 137 |
| Vial 3 | ||||
| Score 1 | 11 | 7 | 1 | 19 |
| Score 2 | 8 | 8 | 1 | 17 |
| Score 3 | 1 | 0 | 0 | 1 |
| Total injections given | 94 | 76 | 71 | 241 |
| Vial 3 (extension) | ||||
| Score 1 | 3 | 6 | 4 | 13 |
| Score 2 | 2 | 2 | 1 | 5 |
| Score 3 | 0 | 0 | 0 | 0 |
| Total injections given | 113 | 91 | 83 | 287 |
DISCUSSION
The first treatment step to be taken when faced with a particular allergic condition is to avoid the allergen causing the patient''s symptoms. This measure can be feasible with certain pneumoallergens, although often at a certain cost as in the case of animal epithelium antigens or those present in the work environment. However, in the case of fungi, household dust mites or pollens, it is not possible to completely avoid all contact of the allergen with the sensitive organ. Hence the need for a specific therapy such as immunotherapy (IT) that can help mitigate the effects produced in allergic patients by contact with the antigens to which they are sensitive.
Recent reviews show that immunotherapy with pollens is effective in the treatment of pollinosis patients (16, 43), and some studies have been performed in patients who are sensitive to Parietaria pollen (17, 18, 20-22, 24, 44, 45), in spite of this being a common allergen source in the Mediterranean area (1-9), where many patients are treated with specific IT.
The relatively insoluble, although metabolizable amino acid L- tyrosine has been utilised as a depot adjuvant for the preparation of IT extracts (46, 47). Glutaraldehyde-modified, tyrosine-adsorbed extracts of different pollens have been studied (48-57) and generally satisfactory results have been obtained. The fact that a placebo control was not used in study is because professional ethics advised against such use, particularly considering the present state of knowledge of the success of IT and of other studies using this product (44, 45).
In our study, we have confirmed the clinical efficacy and safety of IT with a glutaraldehyde-modified, tyrosine-adsorbed Parietaria judaica pollen extract in patients with rhinitis, associated or not with bronchial asthma, who were only sensitive to this pollen. The first group received a preseasonal treatment for three years with 3 injections --one each week-- of increasing doses of a Bencard Tyrosine Parietaria extract, and, one week later, an additional injection from the vial with the highest dose, giving a total of 5,100 Standard Units (SU)/year. The second group received the last dose on 5 occasions, with one week between each dose, being given a total of 15,100 Standard Units (SU)/year.
Our results show a progressive decrease in the nasal (p < 0.0001), conjunctival (p < 0.001), asthmatic (p < 0.005) or palatal itching (p < 0.0001) symptoms. In line with the Parietaria judaica pollination season in our region, the symptoms were most intense in the measurement performed in may, when the quantity of pollen grains per cubic meter is highest, followed by the measurement carried out in february and, finally, that performed in october-november, which accounts for the very low levels in the measurements performed during the latter month. The clinical benefit did not appear to be due to less pollen in the atmosphere during the study.
The skin test showed a significant decrease in sensitivity to Parietaria judaica pollen in the patients in both groups throughout the study (p < 0.001). However, there were no differences between groups. This fact has also been observed in other studies carried out with pollen extracts (58-61). In a co-seasonal study carried out from march to october in 60 patients allergic to grasses, Bousquet et al (58) treated 14 patients with placebo, 16 with an allergoid obtained from a mixture of 6 grasses, 13 with a high molecular weight allergoid containing the same mixture of grasses, and 13 with a Dactilis glomerata extract. They found no differences in the patients treated with placebo but they did find differences in the patients treated with extracts, p < 0.04, p < 0.005 and p < 0.01, respectively. In another randomized, double-blind study comparing a Phleum pratensis extract given preseasonally with placebo in 40 patients allergic to grasses, Varney et al (59) found differences in the decrease in the skin tests read immediately in the treated patients (p < 0.02). Macchia et al (60) studied 37 patients allergic to olive pollen; thirty were treated preseasonally, from october 1985 to april 1986, with four pollen extracts and symptomatic treatment, while 7 only received the medical treatment. No variation was found in reactivity in the skin tests performed on the controls; however, a statistically significant difference was observed in those who received the extract (p < 0.001). In a double-blind, placebo-controlled study (17) performed in 35 patients sensitive to Parietaria judaica pollen in which 18 patients were treated preseasonally with a Conjuvac Parietaria extract and 17 with placebo, no variations were found in the skin tests performed on the control group while, in the treated group, differences were found after 4 (p < 0.05) and 10 months of IT (p < 0.01).
In our patients, the nasal challenge test showed a significant decrease in sensitivity to Parietaria pollen (p < 0.001) throughout the study. Similar results were obtained by Ortolani et al (17) (p < 0.01); Bonifazi et al (44), in a study performed in 30 patients allergic to Parietaria pollen treated preseasonally (15 with Bencard Tyrosine Parietaria and the remaining 15 with Alavac Bencard Parietaria); and in a similar study, carried out in Bari (45) with 22 patients, 11 treated with Bencard Tyrosine Parietaria and the remaining 11 with Alavac Bencard Parietaria.
We have not found any correlation between the reactivity to the allergen in nasal challenge as assessed using objective indices and symptom/medication scores. Some studies (61, 62) have reported such a correlation; Bousquet et al (61) found a statistically significant correlation between nasal challenge and symptoms during grass pollination in patients treated with a grass allergoid. However, our results are not comparable with those of Bousquet et al due to the different techniques used for the nasal challenge and the diffences in evaluating the symptom/medication scores (Bousquet et al assessed the number of days with symptoms).
The IgE counts showed an increase in both treatment groups (p < 0.001) in spite of the patients'' clinical improvement. Among the studies published, some show decreases in the IgE counts (60, 63) --p < 0.001 and p < 0.01, respectively-- while others find no such variation (17) or offer variable results depending on the clinical response (64) and others a small but non-significant increase (65).
The analysis of the IgG figures does not show any significant changes during the first year of treatment (p < 0.01), although during the next two years there is a significant increase in the february and may measurements, particularly during the third year (p < 0.001). The count falls again in the november measurement, some time after the extract was given, although this decrease is less marked in the last year of treatment, suggesting that the immunological changes affecting the IgG gradually regress as the number of months since administration of the IT increases, as repeated treatment increases intensity and duration of action. These findings are in line with those of others (17, 44, 45, 58, 60, 63-65), who also found in increase in IgG levels with immunotherapy.
Unlike the above in vitro tests, the histamine release test shows a progressive decrease throughout the study, following the same trend as the patients'' symptoms and the challenge tests. Likewise, Brunet et al (66) report a smaller seasonal increase in antigen-specific histamine release factor in patients allergic to ragweed treated with immunotherapy.
The tolerance and safety of the Parietaria allergoid can be considered excellent; out of a total of 804 injections carried out during the study period, there were 125 (15.54%) minor local reactions and only 2 severe local reactions (score 3) were recorded (0.25%).
There were no significant differences between the two treatment groups, which implies that an immunotherapy course of four injections with the Parietaria allergoid is sufficient to obtain positive results and no further improvement is obtained when this course is extended. This is contrary to many views that a prolonged immunotherapy course leads to greater benefit for the patient.
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