Occurrence of tumor antigen pRL1a specific CD8 T cells in spleen cells from syngeneic BALB/c, semiallogeneic (BALB/cxC57BL/6)F1 and allogeneic C57BL/6 mice

We investigated the generation of CD8 cytotoxic T-lymphocytes (CTL) that recognized a dominant pRL1a peptide bound to H-2L(d) molecule on RL male 1 leukemia in spleen cells from RL male 1-bearing, syngeneic BALB/c, semiallogeneic CB6F(1) and allogeneic B6 mice by repetitive in vitro stimulation with RL male I tumor. CD8 T cells in cultures were also analyzed by H-2L(d)/pRL1a tetramer staining. We showed that pRL1a-specific CTL were more efficiently generated in spleen cells from RL male 1-bearing high responder CB6F(1) mice than in low responder BALB/c mice, and this correlated well with the occurrence of H-2L(d)/pRL1a tetramer binding CD8 T cells. Furthermore, we showed that in spleen cells from RL male 1-bearing allogeneic B6 mice, H-2L(d)/pRL1a complex specific CD8 T cells were present at a significant frequency. H-2L(d)/pRL1a recognizing B6 CTL but not BALB/c or CB6F(1) CTL gradually lost CD8 expression on their surface by multiplication of in vitro stimulation.