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
Miyawaki, T.; Nagaoki, T.; Yokoi, T.; Yachie, A.; Uwadana, N.; Taniguchi, N.
Journal of Immunology 128(2): 899-903
1982
ISSN/ISBN: 0022-1767 PMID: 6976387 Document Number: 191376
Two distinct human T cell subsets, OKT4+ cell-rich and OKT8+ cell-rich populations, were negatively selected with reasonable purity by complement-mediated cytolysis with the use of monoclonal OKT4 and OKT8 antibodies. B cells were purified by rigorous depletion of sheep erythrocyte rosetting cells. Purified B cells responded to pokeweed mitogen (PWM) to yield a negligible number of Ig-producing cells (Ig-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, Ig-PC. Helper function of each T cell subset was measured as the ability of added T cells to restore the generation of Ig-PC by B cells after 7 days of culture with NWSM or PWM. In the NWSM system, both OKT4+ and OKT8+ subsets, when added back to autologous B cells, markedly enhanced the generation of Ig-PC in a somewhat dose-dependent fashion. Helper cell activity within the OKT4+ subset was twice as intense as that within the OKT8+ subset. In the PWM system, only the OKT4+ subset provided efficient help for B cell differentiation; the OKT8+ subset could not. Suppressor activity was evaluated as the capacity of added T cells to depress Ig-PC generation by B cells in the presence of adequate helper cell function. In the PWM system, the OKT8+ subset, but not the OKT4+ subset, when added to a mixture of autologous B and OKT4+ cells, suppressed the generation of Ig-PC. In NWSM neither OKT8+ nor OKT4+ subsets showed any appreciable suppression on B cell differentiation. Cellular interaction between OKT4+ and OKT8+ cells in suppressing B cell differentiation was analyzed in the NWSM-driven system with the use of PWM-prestimulated T cell subsets. T cell subsets, untreated or prestimulated for 12 h with PWM, were added to autologous B cells in various combinations in culture and were stimulated for an additional 7 days with NWSM. Helper activity for B cell differentiation of untreated or PWM-prestimulated OKT4+ cells was nearly identical. The generation of Ig-PC by B cells under the help of untreated OKT4+ cells was no affected by further addition of untreated or PWM-prestimulated OKT8+ cells. The generation of Ig-PC with the help of PWM-prestimulated OKT4+ cells was depressed to a similar extent by the addition of PWM-prestimulated or untreated OKT8+ cells. Irradiation (2000 rad) of PWM-prestimulated OKT4+ cells in this system abrogated suppression mediated by added OKT8+ cells. 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+ cels in this system and the ability of these OKT4+ cells to interact with OKT8+ cells appeared to be radiosensitive.