POLYCLONAL IgE CLASS - RESTRICTED TOLERANCE

Antibody responses of the immunoglobulin E (IgE) class are regulated by a finely tuned network of cellular and molecular interactions. The differentiation of IgE B lymphocytes is controlled by antigen-specific and non-antigen-specific T helper and suppressor cells and their molecular products (1-3). The antigen-specific cellular interaction can be carried out by thymus-derived (T) cells which recognize immunogenic carriers through the hapten-carrier bridges (4-6). A common idiotypic determinant has been shown in antibody responses of the IgE and IgG classes to the synthetic polypeptide antigen L-glutamic acid-t-alanine-L-tyrosine (7). TEPC-15 (T15) x idiotypic determinant has been shown in serum IgE antibodies specific for phosphorylcholine (PC) (8), and surface tg of IgE precursor cells (9). Idiotypic determinants present on IgE molecules are functionally important in regulating the production of IgE molecules, since suppression of the IgE antibody response to PC can be achieved by isologous anti-T-15 antiserum (8). Recently, the existence of the T-15 idiotypic determinant has also been demonstrated on PC-mycobacteriumprimed T cells, and PC-specific T cell hybridoma (10). Likewise, IgE antibody responses to benzyl-penicilloyl coupled to carrier proteins can be suppressed by isologous antiidiotypic antibodies raised against carrier-specific antibodies (11), which suggests that regulatory T cells may be dampened through the idiotypic determinants of antigen-specific receptors on T cells. More apparent than with other classes of Ig, IgE antibody responses have been found to be stringently controlled by non-antigen-specific IgE class-restricted regulatory cells (1, 12-17) and their molecular products (1, 2, 15-22). Much effort has been directed to elucidate the molecular basis of this class-restricted regulation in the IgE antibody system. It has been clearly established by studies conducted in the laboratories of Ishizaka and Kishimoto (10, 15-17, 23) that certain cells and molecules participating in the regulation of IgE antibody response display IgE heavy chain-