Mediation of immunity to tumor isografts in mice by heterologous ribonucleic acid

The growth of tumor isografts in inbred mice is inhibited by intra-peritoneal injections of syngeneic spleen incubated, in vitro, with ribonucleic acid extracted from guinea pigs immunized with the same mouse tumor. This inhibition is partially tumor-specific. Treatment with ribonuclease abolishes the response.