DIFFERENCES IN IMMUNE-RESPONSES TO TUMOR-INDUCED IN SYNGENEIC HOSTS BY INJECTION OF HYBRID AND PARENTAL TUMOR-CELLS

Immunization of C3H/He mice with L-FM3A#2 hybrid cells, made by fusion of ascitic mammary carcinoma FM3A#2 cells with 8-azaguanine resistant L(AG) cells, both of C3H/He mouse origin, resulted in spleen T cell-d ependent resistance to the parental FM3A/R cells. These spleen T cells , purified by passing through a nylon fiber column, could be demonstra ted to have Thy-1.2 and Lyt-2.1 antigens, and not L3/T4 antigens. Afte r immunizing with irradiated FM3A/R cells, cytotoxic cells other than cytotoxic T lymphocytes (CTL) appeared, these presumably being nonphag ocytic macrophages or polymorphonuclear cells. In this case, anti MM a ntiserum was generated at an earlier stage than when mice were immuniz ed with the L-FM3A#2 cells. The cytotoxic mechanism is discussed as to the significance of the surface antigen.