The IgE antigen receptor: A key regulator for the production of IgE antibodies

Immunoglobulins in general form a substantial component of serum proteins, and play a role in homeostatic mechanisms, a first line of defense against pathogenic organisms and in immunological memory. In the secreted form, imm unoglobulins represent the effector arm of the humoral immune system. Howev er, immunoglobulins are not only secreted, but can also be expressed on the surface of a B lymphocyte (membrane immunoglobulin), and, in this physical state, most likely convey signals to steer the B cell along its differenti ation pathway. A step forward in the understanding of the role of membrane immunoglobulins other than membrane IgM or IgD was achieved with two mouse lines with mutations in the epsilon heavy chain gene. In IgE(Delta M1M2) mi ce serum IgE is reduced to less than 10% of normal mice, while IgE(KVK Delt a tail) mice show a reduction of 50%, reflecting a serious impairment of th e IgE-mediated immune response. We think that the cytoplasmic tail of IgE i s involved in a signal transduction which leads to the expression of high q uantities and qualities of secreted IgE immunoglobulins, Copyright (C) 2001 S. Karger AG,Basel.