Induction of suppressive cells within the T4 subset by a human T-T hybridoma-produced factor

This study examines the target cell and the mode of action of a factor (TsF), produced by a human T-T hybridoma, which suppresses pokeweed mitogen-induced B cell differentiation as previously reported (J. Immunol. 1982. 129: 1008.). The suppressive effect still exists when peripheral blood leukocytes are depleted of T8+ cells or when TsF is added to a mixture of purified T4+ and B cells. This suppressive effect disappears when the T4 cells are irradiated. The suppression, however, is restored when a large number of T8 cells are added to the irradiated T4 cells. Lastly, a 24 h preincubation of T4 but not T8 cells, with TsF is able to generate suppressive effectors. These results suggest that the target cell for TsF is a radioresistant T4 cell which, upon activation, is able to induce radiosensitive T4 or T8 cells to suppress B cell differentiation.