In vitro studies of cell-mediated immunity to Moloney murine leukemia virus and Moloney leukemia-associated surface antigens.

Cell-mediated immunity to Moloney murine leukemia virus (M-MuLV) and to tumor-associated surface antigens of leukemia cells induced by the virus was studied with an in vitro migration inhibition factor assay. Spleen cells of C57BL/6N mice at Day 14 following inoculation with Moloney murine sarcoma virus, produced migration inhibition factor in response to M-MuLV. The Moloney murine sarcoma virus-immune spleen cells, however, did not respond to other murine type C viruses, to AKR and Rauscher viruses, or to murine mammary tumor virus. The immune spleen cells also responded specifically to purified glycoprotein with molecular weights of 69,000 and 71,000 and proteins with molecular weights of 30,000 and 12,000, but not to protein with a molecular weight of 10,000, of the homologous M-MuLV. Migration inhibition factor production was also observed in response to soluble 3 M KCl extracts of leukemia cells, MBL-2, induced by M-MuLV. Similarly, the immune spleen cells responded to membrane fractions purified from the MBL-2 cells. Comparable membrane fractions prepared from a Gross virus-induced leukemia, E male G2, and a radiation-induced leukemia, RL male 1, were not active. The tumor-associated surface antigens of MBL-2 membranes could be solubilized by the detergent, Nonident P-40. Thus, C57BL/6N mice inoculated with Moloney murine sarcoma virus developed cell-mediated immunity to envelope and some internal antigens of M-MuLV and also to tumor-associated surface antigens of a tumor induced by this leukemia virus.