Rejection of murine cardiac allografts. I. Relative roles of major and minor antigens.

The relative contributions of incompatibilities for class I, class II, or minor antigens to primarily vascularized graft rejection have not been previously compared in large numbers of strains. In our experiments, murine primarily vascularized heterotopic cardiac graft rejection was studied in 16 donor-recipient strain combinations, representing different precisely defined major and/or minor histoincompatibilities. Complete major incompatibilities generally produced strong graft rejection, although it was confirmed that prolonged survival occurs in certain combinations that are incompatible for class I, or class I plus class II, antigens. In addition, however, strong rejection of these grafts was produced in some recipient strains when the donor was incompatible only for minor antigens. This strong effect of minor antigens may reflect their strong stimulation of delayed-type hypersensitivity, whereas the influence of class II antigens seems more related to stimulation of mixed lymphocyte culture generation of lymphocyte-mediated cytotoxicity.