Purification and characterization of a novel isoallergen of a major Bermuda grass pollen allergen,Cyn d 1

A novel immunoreactive isoallergen of a major Bermuda grass pollen allergen, Cyn d 1, was purified by the use of a combination of various chromatographic techniques, including high-performance liquid chromatography. This new isoallergen has a pI value of 9.1 and shows significant N-terminal sequence homology with other isoforms. Carbohydrate composition analysis revealed a 10.4% carbohydrate content consisting of 7 different sugar moieties, including arabinose, fucose, galactose, glucose, mannose, xylose and N-acetylglucosamine, as well as a trace amount of rhamnose. Upon periodate oxidation, the binding activities of the Cyn d 1 isoform to murine monoclonal antibodies and human serum IgE and IgG were reduced, suggesting the importance of the carbohydrate moiety in the immune response. The availability of the purified Cyn d 1 basic isoform will allow for further structural and immunological characterization, and ultimately for the design of an appropriate therapy.