Histamine release from human leukocytes by anti-IgE antibodies: influence of multiple or single epitope recognition.

Upon comparing several polyclonal anti-IgE antisera (specific for the Fc epsilon fragment) for their ability to release histamine, we observed a marked heterogeneity of response for the same antiserum in different cell donors as well as for different antisera in the same cell donor. Additional studies with monoclonal antibodies directed against various epitopes of the D1 and D2 regions revealed several possible explanations: broad specificity of the polyclonal antisera, lack of availability of some epitopes on the cell-bound IgE (which were available on soluble IgE), microheterogeneity among IgE molecules from different patients, and failure of some donors' cells to respond to anti-IgE antibodies. We conclude that selection of appropriate antisera is an important consideration in comparing IgE-mediated histamine release among individuals.