Anti-IgE antibodies in human serum: occurrence and specificity.

An IgG type of antibody directed against IgE has been studied in serum from healthy and allergic individuals. The technique used is based on adsorption of the IgG fraction in serum to protein A-Sepharose followed by reacting any specific antibody with 125I-IgE. The anti-IgE antibodies were partially blocked by endogenous IgE, indicating the presence of IgE-containing immune complexes in serum. Heating of serum to 56 degrees C disrupted the immune complexes, thereby facilitating the detection of anti-IgE antibodies. The antibodies were essentially directed against the heat-labile D epsilon 2 antigen. Significantly raised (p less than 0.001) levels of anti-IgE antibodies were found in patients suffering from allergic asthma, as compared with non-allergic blood donors.