Seasonal changes in IgE antibodies and their relationship to IgG antibodies during immunotherapy for ragweed hay fever.

Seasonal changes in IgE antibodies and their relationship to IgG antibodies were studied in 52 patients with ragweed hay fever and 10 normal controls. Allergic patients received either no immunotherapy, preseasonal immunotherapy, or high dose perennial immunotherapy with aqueous-mixed ragweed extract. Serums were collected before, during, just after, and 4 mo after the ragweed pollination season. IgE antibodies to ragweed antigen E (AgE) were measured using the radioallergosorbent test, and IgG antibodies were measured by radioimmunoprecipitation.IgE antibodies to AgE were elevated in all allergic patients, and rose during the ragweed pollination season. The magnitude of the rise in IgE antibody was a function of the preseasonal IgE antibody level. IgE antibody production in the treated groups was the same as in the untreated group when patients were matched on the basis of their preseasonal IgE antibody levels. Thus, we were not able to confirm previous reports that immunotherapy suppresses the seasonal rise in IgE antibodies. Furthermore, there was a close relationship between the levels of IgE and IgG antibodies in the high dose group. This finding is contrary to what one would expect were IgG antibodies acting to suppress the formation of IgE antibodies. Rather, it suggests that in certain patients either humoral immunological reactivity to ragweed antigens in the IgG and IgE classes is low to begin with or that this reactivity may wane after treatment with high doses of ragweed extract.