Transfer of Tumor-Specific Immunity With RNA: Demonstration by Immune Cytolysis of Tumor Cells in Vitro

Summary

Extracts rich in RNA were prepared from the spleens of inbred strain-2 guinea pigs that had been immunized with a 3-methylchoI-anthrene-induced, strain-2 liposarcoma (MCA-A). Normal, nonimmune, strain-2 lymphoid cells incubated with these RNA preparations caused specific immune cytolysis of MCA-A cells in vitro. Treatment of the active RNA preparations with ribonuclease resulted in their complete inactivation. RNA from the spleens of guinea pigs not exposed to the tumor was ineffective. Incubation of lymphoid cells with extracts of MCA-A rich in solubilized tumor-specific antigens did not reproduce the immune cytolysis caused by the active RNA preparations. Spleen cells incubated in RNA extracted from strain-2 guinea pigs immunized with MCA-A did not cause significant immune cytolysis when applied to monolayers of MCA-25, a strain-2 sarcoma whose tumor-specific transplantation antigens do not cross-react with MCA-A.