Immunoglobulin E. Current status and clinical laboratory applications.

Reaginic antibodies belong to IgE, which represents a distinct immunoglobulin class. Human IgE binds with basophil granulocytes and mast cells through the Fc portion of the molecules and mediates the release of chemical mediators that cause allergic symptoms. The initial step of the reaginic hypersensitivity reaction is probably the bridging of cell-bound IgE antibody by antigen. The reaction appears to initiate enzymatic sequences that lead to the release of chemical mediators. Measurement by radioimmunoassay of IgE and IgG antibodies in ragweed-sensitive hay fever patients has revealed immunologic effects of hyposensitization treatment. Experimental models for the immunotherapy in inbred mice strongly suggest that the major immunological effect would be depression of helper function of antigen-specific T cells. The results suggest logical approaches to improve the effect of the treatment.