Lymphomas in BALB/c Mice Inoculated With Supernatants From Chemically Induced Sarcomas 2 3

Abstract

To determine if acellular extracts from primary sarcomas induced by 3-methyl-cholanthrene (MCA) could be oncogenic, BALB/c mice were inoculated with supernatants from these tumors. A single inoculation at birth raised the incidence of lymphoid neoplasms from 7 to 45% at 18 months. The increase was remarkable (0–100% at 18 months) when fresh tumor supernatants were repeatedly injected into young mice. These results could not be matched by replacing tumor tissue by normal, regenerating, embryonic, or necrotic tissues in control procedures. Similar results were not obtained with different mouse strains and tumor filtrates instead of supernatants. These findings, obtained under conditions which excluded cell transplantation or transfer of chemical carcinogen, indicated that prjmary MCA tumors contained a nascent murine leukemia virus (MuLV) to which BALB/c mice were susceptible. To confirm this assumption, several individual MCA tumors and normal tissues were tested for the presence of MuLV with the XC syncytium assay. Virus activity was detected in 6/14 individual tumors, 1/7 tissue samples from normal mice, and 2/8 normal tissue samples from tumor-bearing mice. Titers were higher in tumors. Although nascent MuLV was more likely to be found in MCA tumors than in normal tissues, we could not ascertain whether its presence was necessary or accidental in chemical oncogenesis.