Cytolytic thymus-derived lymphocytes specific for allogeneic stimulator cells crossreact with chemically modified syngeneic cells.

Mouse spleen cells cocultured with irradiated allogeneic stimulator cells develop cytolytic effector cells capable of lysing 51Cr-labeled syngeneic trinitrophenyl-derivatized tumor or spleen targets and to a lesser degree unconjugated tumor cells in addition to the allogeneic stimulator cells. Lysis of trinitrophenyl-syngeneic targets was inhibited competitively by cold trinitrophenyl-syngeneic tumor or spleen targets as well as by cells bearing the allogeneic stimulator H-2 haplotype demonstrating the immunological specificity of the interaction. Allogeneic H-2 specificities may, therefore, be considered variants of modified autologous H-2 specificities against which cytolytic thymus-derived clones potentially exist that are capable of exerting immunological surveillance.