[High-polymeric xenogenic RNA as an antitumor immunity stimulator]

To immunize CC57BR mice a suspension of live cells of Krebs-2 ascites tumour was administered intradermally into the tail partially amputated afterwards. The growth of the tumour transplanted intraperitoneally was inhibited by 23% only after twofold immunization. Single immunization with tumour cell incubated with the cattle liver RNA preparation in conjunction with intraperitoneal administration of RNA following tumour transplantation inhibited its growth by 43--53%, while twofold administration by 84--88%. The high polymeric fraction of the preparation enhanced the immunization effect to the same measures the initial overall preparation. The treatment of the preparation with RNAase and partial depolymerization of RNA in the course of isolation resulted in the activity loss. It is concluded that the capacity of the RNA preparation for stimulating antitumour immunity is due to high polymeric fraction of RNA.