Immune suppression genes control the anti-F antigen response in F1 hybrids and recombinant inbred sets of mice.

The immune response to the liver protein F antigen which, in the mouse, occurs in two allelic forms, is under sharp immunogenetic control in that only mice that possess the Ak molecule can respond to allo-F antigen. This response has been studied in a number of F1 hybrids between inbred strains and with recombinant inbred lines all of which express Ak, and which thus enable immune suppression effects to be detected. In the AKXL and AKXD sets the hybrids with CBA are responders if H-2k/H-2k, and usually nonresponders if H-2k/H-2b or H-2k/H-2d. Although this may be due to gene dosage effects, this cannot be the explanation for the low responsiveness of the H-2k/H-2b relative to the H-2k/H-2d mice found in CBA x BXD hybrids. For this, and other reasons, it seems likely that low responsiveness in any mouse possessing a responder Ak allele is due to suppression, and that this is mediated by the immune suppression effects of the non-H-2k haplotype. These H-2-mediated effects can be modified, both positively and negatively, by background genes. Thus, of the ten H-2k/H-2d members of the CBA x AKXD cross, seven are low responders and three are high responders. No other typed marker has the same strain distribution pattern at present. Major unresolved questions, therefore, concern the location and mechanism of action of the background genes and the mechanism of action of the H-2 immune suppression genes.