Background: Many studies have shown that specific immunotherapy may preventthe development of allergies to new allergens. Recently, however, there have been sporadic reports onthe possibility of new allergies developing during immunotherapy. The aim of this study was to evaluatethe possibility of the occurrence of food allergy and changes of sIgE concentration in patients sensitiveto tree pollen during specific immunotherapy Material/Methods: We examined 12 patients subjected to desensitizationtreatment of pollinosis caused by allergy to the pollen of Betulaceae trees, in whom only Bet v 1 sIgEwas found in serum prior to immunotherapy. The control group included 8 allergic patients who did notconsent to this treatment. Results: Bet v 2 sIgE was detected after 6 months in 3 patients (25%) andafter 18 months in another 2 patients (41.7% total). In 2 cases, oral allergy syndrome (OAS) occurredin the course of therapy. These findings were accompanied by a concomitant decrease in nasal and ocularallergic signs during the birch pollen season in the overwhelming majority of patients (91.7%). In thecontrol group, no serum occurrence of Bet v 2 sIgE was found during the 18-month observation period.Although no OAS signs appeared in any patient, the symptomatic intensity of pollinosis was not reduced.Conclusions: Due to the limitations of currently used vaccines, new allergies may be induced during immunotherapy.In sporadic cases these may be accompanied by the occurrence of specific clinical manifestations, usuallymild.

Keywords: Betula - immunology, Desensitization, Immunologic - adverse effects, Food Hypersensitivity - etiology, Food Hypersensitivity - immunology, Hypersensitivity - immunology, Hypersensitivity - therapy, Immunoglobulin E - blood, Pollen - immunology, Syndrome, Betula - immunology, Desensitization, Immunologic - adverse effects, Food Hypersensitivity - immunology, Hypersensitivity - therapy, Immunoglobulin E - blood, Pollen - immunology, Syndrome