Detection of Type-Specific Antigenic Determinants of Murine Mammary Tumor Viruses with Cell-Mediated Immune Assays

Exposure of lymphoid cells from normal and mammary tumor-bearing Balb/cCrgl mice to MMTV antigens result in positive responses in blastogenic transformation and migration inhibition reactions. The levels of these responses appear to depend on the murine strain source of the viral preparations. Enhanced reactivities were observed in cultures exposed to purified MMTV from culture fluids of mammary tumor cells of spontaneous origin in the C3H strain when compared to purified MMTV derived from milk of mice from the RIII strain. To ensure the virus relatedness of the differences observed, MMTVs obtained from a common source, i.e., the Crandall feline embryo kidney cell line, were employed in blastogenesis assays. Parallel testing of feline cell-derived C3H, RIII, and GR mammary tumor viruses resulted in different levels of [³H]thymidine incorporation by spleen cells from Balb/cCrgl mice over a range of viral concentrations. These results indicate that it is possible to detect various types of MMTV variants with cell-mediated immune assays. The diverse functional reactivities elicited by these viruses may be related to the differences observed in their bioactivities as determined by incidence and development of mammary tumors and the potential of causing metastases.