Functional analysis of two human T-cell subpopulations: help and suppression of B-cell responses by T cells bearing receptors for IgM or IgG.

TLDR

Human peripheral blood was used to isolate thymus‑derived T lymphocytes bearing either IgM or IgG receptors. IgM‑bearing T cells (T.M) dose‑dependently aid B‑cell differentiation, whereas IgG‑bearing T cells (T.G) suppress B‑cell proliferation in the presence of T.M, a suppression that requires prior immune‑complex interaction and is radiosensitive, highlighting distinct helper and suppressor T‑cell subsets.

Abstract

Subpopulations of thymus-derived T lymphocytes bearing receptors for either IgM or IgG molecules were isolated from human peripheral blood. Those with receptors for IgM (T.M) provided help in a cell dose-dependent fashion for the pokeweed mitogen-induced differentiation of B lymphocytes in vitro, whereas cells with receptors for IgG (T.G) did not. T.G cells, on the hand, efficiently suppressed the differentiation and proliferation of B cells in the pokeweed system in the presence of helper T.M cells. This suppressive activity of T.G cells required prior interaction of the T.G cells with immune complexes. The helper activity of T.M cells was relatively radioresistant while the suppressor activity of T.G cells was radiosensitive. The results indicate that helper and suppressor functions of human T lymphocytes in this model system are mediated by different subpopulations of T cells which can be distinguished by their ability to bind IgM or IgG immune complexes, respectively.