Genetic control and effector cells in host-versus-graft responses to H-Y antigen in mice.

T cell responses to the male-specific H-Y antigen in mice include skin graft rejection, delayed-type hypersensitivity and cytotoxic T cell responses; these are under complex H-2 and non-H-2 Ir gene control. The effector cells for these two in vivo responses are Ly 1+2-, and the cytotoxic T cell effectors generated in secondary mixed lymphocyte reactions in vitro are Ly1+2+, although their development requires the presence of Ly 1+2- T helper cells. We investigated the Ir gene control of another in vivo response to H-Y, the host-versus-graft response (HVGR), measured by popliteal lymph node enlargement. The strain distribution pattern (SDP) of primary and secondary HVG responses to H-Y indicates that there are both H-2 and non-H-2 Ir genes involved in controlling responsiveness. Cell transfer of the secondary response identifies an Ly 1+2- effector T cell for this response: this information together with the SDP of cytotoxic T cell responses suggests that the HVGR may represent activation of the T helper population involved in the generation of cytotoxic T cells.