Serial studies on the functional affinity and heterogeneity of antibodies of different IgG subclasses to phospholipase A2 produced in response to bee-venom immunotherapy.

High functional affinity and high titer IgG4 antibodies to phospholipase A2 were produced by allergic patients in response to bee-venom immunotherapy. In contrast, the affinity of IgG1 antibodies decreased after immunotherapy, and both the titer and affinity of IgG1 antiphospholipase A2 remained significantly lower compared to IgG4 1 to 2 years after treatment. Analysis of affinity heterogeneity suggested a loss of IgG1 high-affinity antibody-producing clones during immunotherapy and a preferential expansion of IgG4 clones. High-affinity IgE antibodies were found in untreated allergic patients, and preliminary results suggest that immunotherapy may result in an early marked decrease in the affinity of IgE antibodies.