Cell-mediated cytotoxicity to moloney sarcoma in syngeneic and allogeneic rats

Cell-mediated cytotoxicity in the primary immune response to Moloney sarcoma tumor (MST) in allogeneic and syngeneic rats was found to be predominantly T-cell-dependent. A minor non-T-cell cytotoxic activity may also have been detected. CMC was presumably directed against tumor and viral related antigens in the syngeneic host and primarily against alloantigens in the allogeneic host. CMC was more virgorous in the syngeneic host. This may be due to differences in quantities or immunogenicities of the various antigens involved. Two peaks of T-cells in effector populations were observed during a 20-day post-inoculation period. The first peak corresponded to peak T-cell-mediated cytotoxicity on day 8 and the second peak occurred on days 13 or 14 when CMC was minimal or undetectable.