Effect of cortisone on oncogenesis by murine sarcoma virus (Moloney).

The role of cortisone in viral carcinogenesis was investigated by inoculating murine sarcoma virus (Moloney) into normal BALB/c and C57BL/6 weanling mice and into mice of the same strains pretreated with 2.5 mg of cortisone acetate. The two strains were equally susceptible to tumor induction. Pre treatment with cortisone increased their susceptibility to oncogenesis. Fifty-four out of eighty normal mice developed tu mors in contrast to 78/79 cortisone-treated mice. All tumors induced in normal mice ultimately regressed. However, only 26/78 tumors induced in cortisone-treated mice regressed. All mice were bled 21 days after virus inoculation and their sera were tested against Moloney lymphoma cells by the indirect fluorescent antibody test. Cortisone did not significantly alter the production of the antibody. Tumors induced in normal and cortisone-treated BALB/c mice were assayed for viral activity by tumor induction in vivo and focus formation in vitro. The results obtained from both assay systems indicated that more virus was present in tumors induced in cortisone-treated animals.