IMMUNE-RESPONSES TO NEMATODE EXOANTIGENS - SENSITIZING ANTIBODIES ANDBASOPHIL HISTAMINE-RELEASE

High levels of IgE and eosinophilia are found in both allergy and helm inth infections, but allergic symptoms are rare in naturally acquired helminth infections. The interrelation of specific IgE antibodies and in vitro basophil histamine release (HR) induced by exoantigens from t he larval stages (L2/L3) of the nematodes Toxocara canis and Ascaris s uum was examined in 148 patients visiting an outpatient clinic for par asitic diseases. The antigen sensitivity of the basophils was found to be dependent not only on the absolute amount of antigen-specific IgE present in patient plasma, but also on the ratio between specific and total IgE. Thus, large HR was observed in some patients in response to helminth antigens despite low levels of both specific and total IgE c ontent in plasma. Patients with eosinophilia showed greater IgE-mediat ed HR than the other patients examined. In contrast, only five patient s showed HR after challenge with anti-IgG4, despite the presence of hi gh levels of antigen-specific IgG4 and IgG1 in all patients showing sp ecific IgE antibodies.