Glycoprotein allergens in pollen of timothy. V. Significance of the carbohydrate moiety for the immunological activity of a basic glycoprotein allergen.

When the allergen was oxidized with periodate the size of its precipitate in rocket immunoelectrophoresis (RIE) was reduced. Incubation of the allergen with various glycosidases did not significantly affect its precipitation in RIE. The binding of human IgE and IgG to allergen bound to nitrocellulose seemed not to be affected by incubation with alpha-L-fucosidase, beta-D-xylosidase, beta-D-galactosidase or periodate oxidation. Incubation with alpha-D-mannosidase reduced the binding of IgG to the allergen but not its binding of IgE. Periodate oxidation did not significantly affect the IgE binding of the allergen in radioallergosorbent test (RAST) inhibition. When RAST discs of the allergen were incubated with alpha-D-mannosidase, alpha-D-galactosidase, Arachis hypogaea lectin and concanavalin A, the IgE binding to the discs was slightly reduced. Pretreatment of the discs with the monoclonal antibody FMC-A9 against ryegrass pollen allergens and beta-D-xylosidase did not reduce their IgE binding. L-Arabinose, D-mannose, methyl-alpha-D-mannopyranoside, D-galactose, D-glucose or the monoclonal antibody FMC-A9 did not inhibit the binding of IgE to RAST discs of the allergen. After incubation of the allergen with pronase, it did not form a precipitate in RIE and its IgE-binding ability in RAST and RAST inhibition was almost completely lost.