Structure and Function of Fc Receptors for IgE on Lymphocytes, Monocytes, and Macrophages

Abstract

This chapter establishes that the Fc fragment of immunoglobulins E (IgE) binds with high affinity to specific cell surface receptors (FcɛR) on basophils and mast cells and that cross-linking of FcɛR by antigen–IgE antibody complexes, aggregated IgE or anti-IgE receptor antibodies induces histamine release from these cells. Immunologists were somewhat surprised when it was found that radiolabeled aggregated IgE binds to human lymphocytes and an IgE-dependent killing of schistosomules by rat macrophages (MФ) was described, two observations that suggested the presence of FcɛR on lymphocytes and MФ. Several other researches on the interaction of IgE with lymphocytes and MФ established that these cells carry specific IgE Fc receptors, albeit of a different nature than those on basophils and mast cells. By employing methods involving multiple IgE–FcɛR interactions, such as rosette formation with IgE-coated erythrocytes, cells expressing low-affinity FcɛR can be detected relatively easily. The binding properties of radiolabeled IgE to FcɛR+ human cultured lymphoblastoid cells mouse lymphocytes, cultured human U937 MФ and The binding properties of radiolabeled IgE to FcɛR+ human cultured lymphoblastoid cells, mouse lymphocytes , cultured human U937 MФ have been reported.