Biochemical and immunochemical characterization of hop-hornbeam (Ostrya Carpinifolia Scop.) pollen

Abstract

In the last few years Ostrya carpinifolia pollen is considered as an important cause of respiratory allergy in Mediterranean areas. The concentration of the pollen was measured over a period of fifteen years from 1981 to 1996 in an area around Genoa; the results of this study have clearly indicated an increasing trend that correlate with persons sensitization. In this study we sought to define the immunochemical and biochemical properties of hop-hornbean pollen. Soluble proteins extracted from Ostrya carpinifolia pollen and from the taxonomically related species Corylus Avellana, were analyzed by polyacrylamide gel electrophoresis (SDS-PAGE), by horizontal isoelectrofocusing (IEF) and by two dimensions electrophoresis (2D-PAGE). Allergenic proteins were identified with sera of sensibilized patients and cross-reactivity was evaluated by immunoblotting techniques. The electrophoretic analysis showed a partial identity between the proteins from Ostrya and Corylus extracts. The immunoblotting assay, developed with human IgE from subjects allergic to hop-hornbeam pollen, displayed the major IgE reactivity for a component with a molecular weight of 17 kDa expressed in both Ostrya and Corylus extracts. This reactivity is consistent with the presence of Bet v 1 that is described as the major pollen allergen in the Betulaceae and Corylaceae families. Sera from subjects allergic to Ostrya were then preadsorbed with recombinant Bet v 1 immobilized in the Pharmacia CAP System; a significant reduction of the IgE binding activity was observed after the treatment. We therefore suggest that Bet v 1 could be one of the allergenic proteins present in the Ostrya pollen possibly being responsible for cross-reactivity with other members of taxonomically related families.