Regulation of B cell immunoglobulin secretion by functional subsets of T lymphocytes in man.

Two distinct immunoregulatory T cell subsets, termed T4+ and T5+, have been defined in man by monoclonal antibodies. Prior studies have shown that the T4+ T cell population provided help for B cell immunoglobulin (Ig) production and was required for generation of T5+ cytotoxic effector cells. In the present study, the regulatory effects of the T5+ T cell subset on B cell Ig secretion were determined in a pokeweed mitogen-driven system. It was found that the T5+ subset, in contrast to the T4+ subset, was incapable of providing help to B cells and, more importantly, could suppress Ig secretion by B cells in the presence of T4+ inducer T cells, Given earlier studies demonstrating that the T5+ T cell subset suppressed T cell responses as well, this population appears to represent the major suppressor subset in man for T-T and T-B interactions.