Expression of Differentiation Antigens Cross-Reactive with Ly-6.2 Alloantigens on MM102 Mouse Mammary Tumor Cells

: The present study was carried out to investigate the immunobiological nature of alien antigens which appear as tumor-associated transplantation antigens (TATA) on MM102 mammary tumor cells. Anti-MM102 tumor-specific anti-serum obtained was used for examining the expression of antigens cross-reactive with TATA of MM102 tumor on lymphoid cells from allogeneic mice. The results demonstrate that this antiserum exhibited an appreciable degree of reactivity against C57BL/6, but not against C3H/He or BALB/c spleen cells. Further analysis revealed that thymocytes and bone marrow cells were marginally susceptible to treatment with anti-MM102 antibody plus complement. In contrast, portions of peripheral T and B lymphocytes were found to exhibit such cross-reactive antigens. It was also demonstrated that the strain distribution of expression of MM-TATA-cross-reactive antigens was completely correlated with that of Ly-6.2 alloantigens. Moreover, anti Ly-6.2 monoclonal antibody lysed MM102 tumor cells in the presence of rabbit complement. These results indicate that TATA of MM102 tumor cells are cross-reactive with differentiation antigens which develop on allogeneic lymphoid cells and are closely related to Ly-6.2 alloantigens.