Interactions of major and minor histocompatibility antigens in the graft-versus-host reaction.

The greater severity of the graft-versus-host (GVH) reaction induced by grafting C57BL/6(B6) lymphoid or bone marrow cells to irradiated (B6 x DBA/2)F1 recipients, as compared to that induced in H-2-identical (B6 x BALB/c)F1 recipients, has been shown to arise from a synergistic effect of H-2d and DBA/2 minor histocompatibility antigens (MiHAs), and not from a difference in the intensity of genetic resistance to B6 cell grafts exhibited by the two F1s. Furthermore, detection of such synergistic effects depends upon choice of an appropriate assay system; GVH splenomegaly results cannot be used to predict the outcome of a systemic GVH reaction.