Role of mouse IgG and IgE homocytotropic antibodies in passive cutaneous anaphylaxis.

The role of the mouse homocytotropic antibodies in passive cutaneous anaphylaxis reaction was investigated. One class of antibody was heat stable, detected at 2 h but not at 48 h after passive transfer, and belonged to a sublcass of mouse IgG. The other was heat labile, detected at 2 h and 48 h after passive transfer, and belonged to the IgE class of mouse immunoglobulins. In the presence of IgG, IgE homocytotropic antibody was not detected early after passive transfer. This was thought to be due to a masking of IgE by IgG antibodies rather than a competition for mast cell surface receptors, since inhibition studies with rat IgE myeloma protein suggested that mouse IgE and IgG1 may have different receptor sites on mast cell surfaces.