Cell-mediated anti-tumor response in the RL♂61 system II. Control of the T killer cells by an H-2-linked Ir gene interfering with non-H-2 factors

The generation of cytolytic T lymphocytes (CTL) during the immune response directed against the syngeneic X-ray-induced BALB/c RL♂ 1 leukemia has been described previously: T killer cells react with a tumor antigen of RL♂ 1 cells, and the H-2D^d molecules of the target cells play some role in the interaction. The study of anti-RL♂ 1 responses of [(C57BL/6 × BALB/c) × BALB/c] mice shows that the major histocompatibility complex controls the anti-RL♂ 1 CTL reaction at a second level, through an Ir gene, with dominant responsiveness, probably mapping to the right of I-B and controlling the high or low-CTL responder phenotype. Another non- H-Associated gene interferes with the H-2-linked Ir gene, a responder allele at the non-H-2 locus, being necessary for the expression of the high-responder phenotype at the Ir gene locus.