IgE antibodies to recombinant pollen allergens (Phl p 1, Phl p 2, Phl p 5, and Bet v 2) account for a high percentage of grass pollen-specific IgE

Background: Pollen from different grass species are some of the most potent elicitors of Type I allergy worldwide. The characterization of antigenic structures and IgE epitopes common to different grass species is relevant to define reagents for diagnosis and specific therapy of grass pollen allergy. Objective: The purpose of this study was to estimate the percentage of IgE directed to common, cross-reactive, or both types of epitopes shared by recombinant pollen allergens (Phl p 1, Phl p 2, Phl p 5, and Bet v 2) and natural pollen extracts from nine different monocots (Anthoxanthum odoratum, Avena sativa, Cynodon dactylon, Lolium perenne, Phragmites australis, Poa pratensis, Secale cereale, Triticum sativum, Zea mays) by using sera from different populations. Methods: Natural pollen extracts from nine different monocot species were characterized regarding their allergen contents by using specific antibodies and by IgE immunoblot inhibition with recombinant allergens. The percentage of grass pollen-specific IgE that was preabsorbed with a combination of recombinant timothy grass pollen allergens (Phl p 1, Phl p 2, and Phl p 5) and recombinant birch profilin (Bet v 2) was determined by ELISA in sera from 193 European, American, and Asian subjects. Results: IgE to recombinant pollen allergens accounted for a mean 59% of grass pollen-specific IgE. A lower inhibition of IgE binding to certain natural extracts (C. dactylon and Z. mays) could be attributed to the absence of immunologically detectable group 5 and group 2 allergens in these species. Conclusion: We define four recombinant pollen allergens that account for a substantial proportion of grass pollen-specific IgE. The recombinant pollen allergens characterized may represent candidates not only for diagnosis but also for patient-tailored immunotherapy of grass pollen allergy.