Mixed lymphocyte reactivity in spleen cells from F-9 tumor-bearing ice. I. Suppressor cell induction and characterization

The immune capacity of spleen cells from F-9 tumor-bearing mice was assessed in a one-way mixed leukocyte culture (MLR) and in MLR mixing experiments. Alloreactivity was found to be significantly depressed in mice bearing palpable tumors. Mixing experiments demonstrated that the reduced alloreactivity was due to suppressor cell activity in the spleens of the tumorous mice. Suppressor cells were characterized as adherent, Ly2⁺ T cells. This study provides the basis for an analysis of the cell surface antigens on F-9 embryonal carcinoma cells which lead to the induction of suppressor T cells in these mice.