Sensitization of T Lymphocytes in Vitro by Syngeneic Macrophages Fed with Tumor Antigens¹

We investigated the interaction between T lymphocytes and macrophages in the in vitro sensitization of lymphocytes against tumor cells. Spleen cells were sensitized in vitro by syngeneic peritoneal macrophages that had been fed with cell-free antigen preparation of syngeneic tumor cells. The sensitized T lymphocytes acquired specific cytotoxic activity in vitro and the capacity to inhibit tumor development in vivo. Allogeneic macrophages, syngeneic fibroblasts, or the antigen preparation by itself were not able to sensitize the lymphocytes against the tumor.