Cellular interactions of human T cell subsets defined by monoclonal antibodies in regulating B cell differentiation: a comparative study in Nocardia water-soluble mitogen- and pokeweed mitogen-stimulated culture systems

Two distinct human T cell subsets, OKT4+ cellrich and OKT8+ cellrich populations, were negatively selected with reasonable purity by C-mediated cytolysis with the use of monoclonal OKT4 and OKT8 antibodies. B cells were purified by rigorous depletion of E rosetting cells. Purified B cells responded to pokeweed mitogen (PWM) to yield a negligible number of immunoglobulin-producing cells (lg-PC), which were identified by a direct immunofluorescence method, after 7 days of culture, and to Nocardia water-soluble mitogen (NWSM) with the generation of a few, but a significant number of, lg-PC. Helper function of each T cell subset was measured as the ability of added T cells to restore the generation of lg-PC by B cells after 7 days of culture with NWSM or PWM. Results indicate that although NWSM by itself did not activate suppressor T cells to become effector cells, OKT8+ cells in the NWSM-driven system were able to exert suppressor effect for B cell differentiation only when used in combination with PWM-prestimulated OKT4+ cells. PWM-prestimulated OKT4+ cells had a pivotal role for the expression of suppressor activity by OKT8+ cells in this system, and the ability of these OKT4+ cells to interact with OKT8+ cells appeared to be radiosensitive