Identification of a 53 kDa protein, as a new high molecular weight allergen from Fraxinus excelsior (Ash) pollen

Background: Fraxinus excelsior (Ash) is a common tree and is important cause of winter–spring pollinosis in many temperate regions in the world. In this study, a high molecular weight allergen from ash pollen was identified. Methods: In all, 20 individuals allergic to ash participated in the study. Characterization and immunoreactivity of ash pollen proteins was performed using sodium dodecyl sulfate polyacrylamide electrophoresis (SDS-PAGE), two-dimensional (2D) gel electrophoresis and immunoblotting. Results: Immunoglobulin E (IgE)-binding proteins with apparent molecular mass ranging from 9 to 110 kDa were detected in ash pollen extract. Serum IgE of 7 (35%) patients reacted with a 53-kDa protein band. Analysis of 2D immunoblots showed several IgE-binding proteins. Moreover, mass spectrometry analysis indicated that the 53-kDa allergen was homologous to calreticulin. Discussion: We defined a novel allergen from F. excelsior pollen with a molecular weight of about 53 kDa. This allergen could be considered as an important high molecular weight allergenic protein for further studies on cross-reactivity and development of diagnostic and therapeutic approaches.