Ir Gene Regulation of The T Cell Dependent Activation of Distinct B Cell Subpopulations

Abstract

Antibody responses to (T,G)-A--L and (H,G)-A--L, and to the TNP conjugates of these polypeptides, are regulated in the mouse by Ir genes encoded in the I-A region of the murine MHC (1–4). Important to understanding the mechanisms by which such genes control immune responsiveness is the identification of those cell interactions which are regulated by Ir genes. It has been demonstrated that at least two pathways exist for the activation of B cells in T dependent antibody responses(5). These pathways differ both with respect to the B cell subpopulations being activated and with respect to their requirements for MHC-restricted T_H cell-B cell interaction. Since Ir gene regulation may in fact represent a specific consequence of MHC-restricted cell interaction, the present studies were carried out to determine the effect of Ir gene influences on the activation of specific B cell subpopulations. Specifically the possibility was examined that Ir genes which regulate B cell activation influence only those cell-cell interactions which are restricted by the products of MHC genes.