Skin graft rejection and delayed-type hypersensitivity responses to H-Y in an I-Ab mutant.

Based on graft rejection in C57BL/6 and B10.A(4R), but not in B10.A mice, skin graft rejection and delayed-type hypersensitivity (DTH) responses to the male HY antigen were considered to be under the control of the "IBb" gene in the mouse H-2 complex. These two phenomena were re-examined in the B6.C-H-2bm12 mutant strain [mutation in the A beta gene in IA leading to an alteration in Iab serologically detected specificities and the inability to generate cytotoxic T (Tc) cells to H-Y]. In this study the bm12 mutant was shown to produce weak DTH responses to H-Y. By contrast, bm12 female mice were unable to reject male skin grafts unless they had received prior footpad priming of male spleen cells, when graft rejection occurred, albeit slowly. In C57BL/6 mice the response to the HY antigen therefore appears to be solely under the control of the IAb gene. In other strains, response/nonresponse is presumably dictated by the ability of IA/IE interactions to produce T-helper responses.