[Appearance of new transplantation antigens in tumor cells treated with RNA]

Immunization of mice with the Wistar rat liver tissue increased their resistance to the subsequent intramuscular transplantation of Krebs-2 tumour cells preincubated with the rat liver RNA and did not affect the transplantability and growth of the same untreated tumour cells. The growth of the tumour cells pretreated with allogenic RNA did not differ from the growth of the untreated tumour cells when the mice were immunized with material genotypically different from the RNA tissue-source. When the immunizing tissue and RNA source were genotypically identical, the mass of the tumours growing in three tested mice strains (A/He, CC57BR, BALB/c) was 40-50% less than that of untreated tumours and the enhancement effect was observed in C3Hf mice. It is suggested that RNA preparations induce the appearance of the transplant antigens in tumour cells similar to those of RNA donors tissues. The effect of RNA preparations was abolished by RNAse incubation.