Allergol et Immunopathol 1999;27(1):1-2
EDITORIAL
NASAL TOPICAL IMMUNOTHERAPY
The treatment of allergic rhinitis always has been a challenge for allergologists because routine therapeutic measures often do not achieve very good results, limited as they are to controlling symptoms with oral or topical antihistamines, corticoids, vasoconstrictors, or cromoglycate, which also can be applied locally. However, in every case the most desirable treatment is an etiological treatment that pinpoints the patient''s sensitivity to the allergens responsible for the process. Conventional subcutaneous immunotherapy (IT) usually does not achieve relevant results. This type of IT benefits patients (1, 2), but it is evident that many asthmatic patients with major symptoms of rhinitis who undergo prolonged desensitization treatment manage to bring their bronchial symptoms under control without eliminating rhinitis, which constitutes so-called residual rhinitis. This is a clear example of the low effectiveness of subcutaneous IT for controlling rhinitis.
Although there are not many publications available on this subject, topical IT seems to be a good solution in many cases. The recently published Position Paper of the EAACI and ESPACI (3) presents 14 studies that have verified the efficacy of this treatment in double-blind, placebo-controlled studies. In these studies, "positive efficacy" was demonstrated in 252 patients compared with ineffective therapy in only 22 patients. No general side effects occurred and local effects were minor.
The mechanism of action of topical IT seems to differ from that of subcutaneous IT because the stimulus is confined to the nasal mucosa, where the immunological reactions take place. A study by Piazza (4) of serum levels of total IgG, IgG4 and IgE in patients with allergic rhinitis before and after treatment with subcutaneous and topical IT, found no significant differences in analytical results with topical IT, although the patient experienced clinical improvement. This indicates that the mechanism of action of topical IT is not the same as that of subcutaneous IT. In topical IT, the stimulus is local and produces an increase in IgA secretion (5) and a decrease in IgE. In an earlier study (6), a reduction in total IgE in mucus was confirmed after a year of topical IT for dust mites; specific IgE increased in some cases and decreased considerably in others. A study by Passalacqua et al (7) has shown that topical IT produced a reduction in the number of eosinophils, neuotrophils, and ICAM-1 in the nasal mucosa in response to nasal provocation with the allergen (Parietaria), a decreased clinical response, and improved symptoms. These improvements persisted after the pollen season. This demonstrates the local anti-inflammatory effect of topical IT and its clinical efficacy.
The practice of topical IT should be based on a correct diagnosis, particularly of local sensitization. Although the ideal situation would be to study total and specific IgE in nasal secretions, this is not always possible. Serum (RAST) and skin tests can suggest the allergen responsible for rhinitis symptoms, then a nasal provocation test with these allergens can be used to confirm the diagnosis by eliciting the typical symptoms (sneezing, watery nose, etc.). Eosinophils in nasal secretions or reduced flow in rhinomanometry may also be studied (8). In this issue of Allergologia et Immunopathologia, Filiaci et al (9) made an objective assessment of the efficacy of topical nasal immunotherapy based on measurements of resistance to nasal airflow by rhinomanometry in response to provocation with the responsible allergen and cold water.
Some drawbacks of topical IT are the prolonged treatment period, which may lead to noncompliance or irregular compliance, and the application technique, which should be taught and controlled to avoid irregularity in the treatment routine. Therapy may be discontinued for intercurrent symtoms originated by a variety of causes. It is difficult to evaluate results because the symptoms of allergic rhinitis appear with other conditions, since they are nothing other than an expression of the general defense mechanisms of the nasal mucosa. This underlines the interest of objective evaluations of results, so that nasal hyperreactivity before and after treatment can be controlled, as Filiaci et al did in their study.
F. Muñoz-López
REFERENCES
1. Norman PHS. Immunotherapy for nasal allergy. J Allergy Clin Immunol 1988;81:992-6.
2. Brunet CH, Bédard P-M, Lavoie A, et al. Allergic rhinitis to ragweed pollen. J Allergy Clin Immunol 1992;89:76-86.
3. Mailing HJ, Abreu-Nogueira J, Álvarez-Cuesta E, Björktén B, Caillot D, Canónica GW, et al. Local Immunotherapy. Position Paper. Allergy 1998;53:933-44.
4. Piazza, et al. Humoral response to subcutaneous, oral and nasal immunotherapy for allergic rhinitis due to dermatophagoides pteronyssinus. Ann Allergy 1993;71:461.
5. Gurgenidze GV, Baraban EL, Gamkrelidze AG. Comparative estimation of general and local humoral immunity indicators in connection with local immunotherapeutic treatment. Allergol et Immunopathol 1990;18:325-9.
6. Martín Mateos MA, Monferrer R, Muñoz-López F. Topical nasal immunotherapy. Immunologic response of IgE in nasal secretion after immunotherapy with Dermatophagoides pteronyssinus. Allergol et Immunopathol 1990;18(4):223-8.
7. Passalacqua, et al. Nasal immunotherapy to Parietaria: evidence of reduction of local allergic inflammation. Am J Respir Crit Care Med 1995;152:461.
8. Rodrigues F, Solé D, Naspitz C, Muñoz-López F. Diagnostic value of nasal provocation testing and rhinomanometry in allergic rhinits. J Invest Allergol Clin Immunol 1996;6(3):184-8.
9. Filiaci F, Zambetti G, Romero R, Ciofalo A, Luce M, Germano F. The non-specific hyperreactivity before and after nasal specific immunotherapy. Allergol et Immunopathol 1999;27(1):24-8.
