RECOMBINANT BIRCH POLLEN ALLERGENS (RBET V 1 AND RBET V 2) CONTAIN MOST OF THE IGE EPITOPES PRESENT IN BIRCH, ALDER, HORNBEAM, HAZEL, AND OAK POLLEN - A QUANTITATIVE IGE INHIBITION STUDY WITH SERA FROM DIFFERENT POPULATIONS

Background: Pollen from trees of the order Fagales are important aller gen sources in most parts of the world. Clinical, immunochemical, and molecular biology studies indicate that they contain cross-reactive al lergens. The major birch pollen allergen, Bet v 1, and birch profilin, Bet v 2, a highly crossreactive allergen, have been cloned and expres sed in Escherichia coli. Objective: The purpose of this study was to d emonstrate the presence of allergens in Fagales pollens that share IgE epitopes with recombinant Bet v 1 and Bet v 2 and to determine the pe rcentage of birch, alder, hornbeam, hazel, and oak pollen-specific IgE that can be preabsorbed with rBet v 1 and rBet v 2 from 102 sera of d ifferent populations of subjects allergic to Fagales tree pollen.Metho ds: The presence of rBet v 1- and rBet v 2-homologous allergens in tre e pollen extracts was investigated by IgE immunoblot inhibition experi ments, and the percentage of tree (birch, alder, hornbeam, hazel, and oak) pollen-specific IgE that was bound by a mixture of rBet v 1 and r Bet v :! was determined by RAST-based quantitative IgE inhibition expe riments. The clinical significance of IgE antibody cross-reactivity wa s studied by skin prick testing with rBet v 1, rBet v 2, and Fagales p ollen extracts. Results: Natural birch, alder, hornbeam, hazel, and oa k pollen contain allergens that share IgE epitopes with rBet v 1 and r Bet v 2. A combination of rBet v 1 and rBet v 2 accounted for82% of tr ee pollen-specific IgE on average. Most of the tree pollen-specific Ig E was directed against rBet v 1. Conclusion: rBet v 1 and rBet v 2 con tain most of the Fagales pollen-specific IgE epitopes and may therefor e substitute natural tree pollen extracts not only for diagnosis but a lso for patient-tailored immunotherapy of tree pollen allergy.