Using a quantitative assay for lymphocyte-mediated cytotoxicity, it was shown that normal nonimmune human lymphocytes were converted to effector cells specifically cytotoxic to human tumor cells in vitro by incubation with "immune" RNA extracted from the lymphoid organs of specifically immunized guinea pigs or sheep. Lymphocytes incubated without RNA or with control RNA preparations failed to show cytotoxic activity. These immune responses were abrogated when the immune RNA was treated with RNAase prior to incubation with lymphocytes. However, treatment with DNAase or pronase did not alter the activity of the immune RNA.
Pilch YH, Veltman LL, Kern DH. Immune Cytolysis of Human Tumor Cells Mediated by Xenogeneic "Immune" RNA. Arch Surg. 1974;109(1):30-34. doi:10.1001/archsurg.1974.01360010022004