Effects of human T-cell subpopulations on B-cell proliferation as determined by (3H)-thymidine incorporation.

Human T-cell subgroups, fractionated by Fc receptor characteristics, have primarily been utilized to investigate their influence on B-cell immunoglobulin synthesis. We have investigated T subpopulation-B cell interaction by evaluating [3H]-thymidine incorporation of pokeweed mitogen-stimulated lymphocytes. DNA synthesis by B cells is dependent on T cells, but may be influenced by regulatory mechanisms that are distinct from those related to plasma cell differentiation. Peripheral blood mononuclear cells were divided into purified B cells, and three T-cell groups [T total (TI), T gamma (Fc receptors present for IgG), and T non-gamma (no Fc receptor on initial isolation)]. A fixed concentration of B cells (5 X 10(4) was then added to increasing concentrations of T gamma and irradiated TI or T non-gamma cells in the presence of PWM. The addition of irradiated T non-gamma enhanced [3H]-thymidine incorporation in a linear dose-dependent relationship. The addition of T gamma cells resulted in reduction in lymphocyte [3H]-thymidine incorporation is an alternative method for the evaluation of T-cell subgroup-dependent suppression or enhancement of human B-cell activity.