[4] Immunoglobulin E (IgE)

This chapter provides an overview of immunoglobulin E (IgE). IgE is the least component of the immunoglobulin family in humans and experimental animals. The concentration of the immunoglobulin in normal human serum is in the order of 100 to 200 ng/ml. However, IgE antibodies have unique biologic activities. The antibodies sensitize mast cells and basophils of homologous species, and the reactions of antigen to cell-bound IgE antibodies induce the release of a variety of mediators, which cause allergic symptoms. Purification of monoclonal IgE is further described. Many investigators tried to purify polyclonal IgE from the serum of atopic patients, serum of rats infected with the nematode, Nippostrongylus brasiliensis and ascitic fluids of mice immunized with an appropriate antigen. Although they succeeded to enrich IgE and to identify the protein, polyclonal IgE has never been purified. So far, only monoclonal IgE is purified from the serum of E myeloma patients, ascites of rats bearing IgE-producing immunocytoma and ascites of mice bearing IgE producing hybridomas. The chapter further explains purification of mouse monoclonal IgE by antigen-coated affinity column.