COMPARISON OF IGE AND IGG ANTIBODY-RESPONSES OF ATOPIC INDIVIDUALS WITH SENSITIZATION TO TREE AND GRASS POLLENS

Sera of atopic individuals with predominant sensitization to either tr ee pollen (TAs) or tree and grass pollens (TGAs) as well as of nonatop ic subjects (NAs) were analyzed for IgE, IgG, and IgG4 antibodies spec ific for grass pollen allergens. Of 600 atopic individuals with serum IgE antibodies specific for birch pollen allergens, 54% also had serum IgE antibodies specific for grass pollen. The mean titers of Ige anti bodies specific for grass pollen proteins were about 10 times higher i n the sera of TGAs than those in the TAs and NAs. SDS-PAGE immunoblott ing analysis of grass pollen proteins using sera of TGAs, TAs, and NAs with respect to the binding of these proteins with IgE and IgG antibo dies in these sera exhibited a similar pattern of variation. Quantitat ion by enzyme immunoassay of the antibody binding to a recombinant gra ss pollen allergen, rKBG8.3, further demonstrated that elevated IgG an tibody levels in TGAs are mainly due to a broader range of specificiti es, and not to high specific binding to the individual protein. Statis tically significant correlation was found between IgE and IgG4 antibod ies specific for the Kentucky bluegrass (KEG) extract, but not for the isolated recombinant allergen. These results indicate that the univer sity of Manitoba grass pollens elicit a complex array of antibody spec ificities in both atopics and nonatopics, and that the profile of anti bodies specific to the pollen extract and pure allergens differs, sugg esting that single grass allergens may be inadequate for replacing gra ss pollen extracts for immunotherapy.