Relationship between allergic status and specificity of IgG antibody to inhaled allergens: the grass pollen model

Background We have previously reported that IgG antibodies from healthy individuals and patients suffering from non-seasonal mite allergy bind to different sets of epitopes on Der p 1, allowing almost complete discrimination of the populations. Objectives To confirm this observation in a seasonal allergy model where a clear relationship between allergic symptoms and exposure to the offending agent is established. To investigate whether the pattern of modified specificity is related to the differences in IgG subclass hierarchy usually exhibited by nonallergic and allergic populations. Methods The capacity of individual sera from patients allergic to grass pollen and healthy individuals, including grass pollen-sensitized subjects, to prevent the binding of pooled IgG, IgG1, and IgG4 fractions from grass pollen-allergic patients and healthy individuals to solid-phase bound grass pollen antigen was evaluated in enzyme-linked immunosorbent assay (ELISA) using streptavidin-biotin technology. Specificity controls were performed using sera from patients allergic to cat dander and house dust mite. Results The capacity of sera to prevent the antigen binding of allergic IgG averaged 84 ± 5% for allergic sera and 53 ± 6% for healthy sera (P