Patients suffering from respiratory birch pollen allergy are also known to be allergic to some foods; for example, stone-fruits, hazelnuts, and some vegetables. The aim of this thesis was to explore clinical and immunological characteristics of birch pollen-related food allergy.
To obtain more clinical information on birch pollen-related food allergies, we analyzed data about the symptoms of Austrian birch pollen-allergic patients (N=225) to particular foods. More than 70% of the study participants indicated that they experienced birch pollen-related food allergy and more than 87% of these food-allergic patients suffered not only during the birch pollen season, but perennially. Apple, hazelnut, and peach were found to most frequently provoke symptoms of the birch pollen-related food allergies, mainly causing oral allergy syndrome. The major birch pollen allergen Bet v 1 was determined as the allergen to which patients with birch pollen-related food allergies are primarily sensitized, whereas the pan-allergen profilin (Bet v 2) was determined to be less relevant.
To obtain more knowledge about immune mechanisms of birch pollen-related food allergies, we explored the function of allergen-specific IgG4 antibodies in immunological cascades of birch pollen-allergic patients who tolerate birch pollen-related foods. We found that individual food-specific IgG4/IgE ratios were significantly higher in patients tolerating either apple or hazelnut than in individuals with an allergy to these foods. Next, recombinant (r) Bet v 1 and rMal d 1, the Bet v 1-homolog in apple, were applied sublingually in allergic patients to study the immune effects in vivo. Sublingual administration of rBet v 1 or rMal d 1 was associated with a transient induction of immune tolerance, possibly mediated by IL-10+Foxp3+ T cells with suppressive function.
In addition, we found that rMal d 1 activated T cells with different epitope specificities and effector functions as compared to rBet v 1 in vivo.
In summary, this PhD thesis provides new insights into clinical and pathophysiological aspects of birch pollen-related food allergy. These insights could be implemented for further developments of diagnostic concepts and effective treatment strategies for this highly relevant food allergy.