Non-H-2 and H-2-linked immune response genes control the cytotoxic T-cell response to H-Y

The immunoregulation of cytotoxic T-cell responses to the male-specific antigen H-Y in mice has been found to be genetically controlled by genes of the major histocompatibility complex (H-2). Responsiveness was mainly confined to H-2b strains, but it has also been found in recombinant strains, F1 hybrids, and chimeras that carry at least part of the H-2b haplotype. By using a different immunization procedure it has been shown recently that an H-2k mouse strain (CBA) is also able to mount an equivalent H-Y-specific response. We investigate here, by applying this immunization technique, the responsiveness of other H-2k strains and of strains of other independent H-2 haplotypes. Both responders and nonresponders are found in three haplotypes: k, s, and d. The strain distribution pattern of responsiveness shows a combined influence of non-H-2 and H-2 genes. In certain strains there is a high variability in responsiveness between genetically identical individual animals. We discuss a model of immune response (Ir) gene function which could account for these observations.