Immunotherapeutic elimination of syngeneic tumors in vivo by cytotoxic T lymphocytes generated in vitro from lymphocytes from the draining lymph nodes of tumor‐bearing mice

The draining lymph nodes (LN) of mice injected with viable syngeneic tumor cells contain populations of lymphoid cells which are capable of generating functional cytotoxic T lymphocytes (CTL) during an in vitro culture period without the need of secondary stimulation with irradiated tumor cells or addition of exogenous cytokines. Intravenous injection of as few as 2.5 x 10(6) tumor-reactive effector cells generated using this protocol effectively eliminated challenges of tumor cells at distal skin sites, whereas injection of cultured control lymphoid cells was ineffective at rejecting tumor challenges. The anti-tumor CTL generated from the draining LN of C57BL10 mice immunized with viable syngeneic tumor cells were found to be specific for the tumor used for immunization both in vitro and in vivo. Phenotypic analysis of the cells responsible for tumor elimination (both in vitro. and in vivo) demonstrated the anti-tumor effector cells to be CD4-CD8+ asialo GM1+NK1.1-. Finally, anti-tumor CTL generated during the short in vitro culture period were able to effectively reject pre-existing tumors in vivo in a systemic fashion. These data indicate that the generation of tumor-reactive CTL from the lymphoid cells contained in the LN draining the site of a tumor may provide a valuable source of effector cells which can be used in the immunotherapeutic treatment of cancer.