Cloning of an IgE Immunoregulatory Factor by Expression in Mammalian Cells

Abstract

T lymphocytes and their products regulate synthesis of immunoglobulin by B lymphocytes at several levels. T-cells may help or suppress immune responses in an antigen-specific or non-specific way, or may regulate idiotype or isotype-specific responses. Several researchers have described isotype specific regulation of the synthesis of IgE, IgA, and IgG in rodents as well as humans. Certain characteristics appear to be common to such regulation: the T cells which regulate the synthesis of a heavy-chain isotype by B-cells bear Fc receptors specific for that isotype and these Fc receptor-bearing lymphocytes secrete factors which are active in regulating immunoglobulin synthesis by B-cells. In general, the soluble factors bind specifically to the Fc region of the immunoglobulin isotype which they regulate, and appear to be related structurally to the lymphocyte Fc receptor. We refer to this family of isotype-specific regulatory factors as “immunoglobulin-binding factors”, or Ig-BF.