Immunological enhancement of murine tumor isografts mediated by RNA from lymphoid organs of xenogeneic immunized animals.

Abstract

Enhanced growth of isografts of a benzpyrene-induced sarcoma (BP-4) was produced in C3H mice by mixing tumor cells in vitro with normal syngeneic spleen cells which had been preincubated with ribonucleic acid (RNA) preparations (BP-4 RNA) extracted from the lymph nodes and spleens of guinea pigs previously immunized with cells from the same sarcoma. RNA from pigs immunized with normal C3H tissues was significantly less effective in mediating enhancement, while RNA from pigs immunized with only Freund's adjuvant was totally ineffective. The response was abolished when active RNA preparations were treated with ribonuclease (RNase). Sera were obtained from mice receiving mixtures of tumor cells and spleen cells which had been preincubated with BP-4 RNA. Such sera contained enhancing antibodies, as evidenced by the enhanced growth of tumor cell inocula when tumor cells were incubated with these sera in vitro prior to their injection into susceptible hosts. The enhancement was specific for the immunizing tumor, since BP-4 RNA mediated enhancement of BP-4, but not BP-1, isografts (a second benzpyrene-induced sarcoma in C3H mice), and BP-1 RNA mediated enhancement of BP-1, but not BP-4, isografts.