[Co-operation among T cells in the development of cell-mediated cytotoxicity]

Lethally iradiated F1 hybrid mice were given an intravenous injection of parental strain spleen cells. Six days later, their spleen cells were used as the effector cells to measure the in vitro cell-mediated cytotoxicity (CMC) of the parental cells. The treatment of the parental donors with hydrocortisone resulted in a marked decrease of the capacity of their spleen cells to produce a CMC reaction, while the treatment with anti-thymocyte serum (ATS) resulted in an almost complete loss of such activity. The mixing of spleen cells from hydrocortisone-treated parental donors with the spleen cells from ATS-treated parental donors before injection resulted in a synergistic amplification of the cytotoxic response. These results demonstrated a synergistic interaction between hydrocortisone resistant T cells and ATS-resistant T cells in the generation of cytotoxic lymphocytes.