Immune Response to a Syngeneic Mammary Adenocarcinoma: I. Comparison of Kinetics of Tumor Cell Growth and Cytotoxic Responses in Syngeneic and Allogeneic Rats

The rat mammary adenocarcinoma 13762A is weakly immunogenic in syngeneic hosts. Transplantation immunity is not developed after injection of irradiated tumor cells. Two cell types were isolated from the tumor: one grew slowly forming solid implants; the second grew rapidly in ascites form, even in allogeneic hosts. Spleen cells cytotoxic for a tissue culture derivative of the tumor were produced in animals after injection of either cell type indicating a common antigen. The kinetics of tumor growth and production of cytotoxic spleen cells were compared in syngeneic and allogeneic animals. In vivo rejection of the tumor in allogeneic hosts did not correlate with the in vitro assay of spleen lymphocyte cytotoxicity. Futhermore, the cytotoxic response of spleen cells from syngeneic tumor-bearing hosts parallels that found in allogeneic hosts.