| Abstract: | The growth of transplanted syngeneic tumors in Wistar/KA (WKA) rats was inhibited by three immunizations with tumors from allogeneic Donryu rats which possibly are unrelated antigenically. Inhibition of syngeneic tumor growth was not associated with the source or type of the tumors (carcinoma and sarcoma) used. A slight inhibition was also observed in rats immunized with a large amount of xenogeneic tumor or allogeneic normal spleen, liver and kidney cells. Inhibition was also observed after immunization with syngeneic tumors artificially infected with murine leukemia virus. However, the inhibition was strongest in rats immunized with allogeneic tumors. The mechanism of inhibition may be immunological, and it may be associated with an increase in the non-specific immunity of the host. |
