Cardiac allograft rejection and enhancement in natural recombinant rat strains

Cardiac allografts were carried out using rat strain combinations with recombinant haplotypes. Rejection times were determined in unsensitized recipients, recipients that had been immunized to produce hyperacute or accelerated rejection, and recipients that had been i.v. immunized with 10(7) bone marrow cells to produce active enhancement. The graft survival results obtained suggest that there is a major influence of the A region or classical type I transplantation antigens in first set and hyperacute rejection whereas immunization to both A or B region (Ia) antigens may produce markedly prolonged survival. These data suggest major differential influences of major histocompatibility complex (MHC) subregions depending on the specific donor-recipient incompatibility as well as suggesting major influences in these three allograft models depending on the background of the strain used.