A model system for determining histocompatibility

Of the many factors that may be significant in permitting successful homotransplantation of tis-sue and organs, there is little question that the genetic relationship of the donor to the recipient will always be of prime importance. In the labora-tory animal, there are many methods of producing permanent or markedly prolonged survival of homografts when major histocompatibility gene loci are the same. In every instance, however, when there is a major genetic incompatibility be-tween donor and recipient, a much more intensive attack is required to accomplish any prolongation of homograft survival. In the human, this is equally true. Where sub-lethal irradiation and uremia are the two major variables affecting homografts, the only perma-nently successful kidney transplant that we have been able to perform has been between nonidenti-cal twins of the same sex (1). These men had 26 identical blood groups, and there was a 26-day survival of skin on the healthy donor from the sick recipient. There is little doubt that the in-herent compatibility in this donor-recipient pair was as significant for success as the other maneu-vers that were carried out. We believe that a con-stant search for methods of assessing histocom-patibility in humans must accompany the exten-sive efforts to permit homograft survival in the animal. Working with normal human volunteers over the past few years, our clinic has demonstrated that a) skin homograft rejection will induce a * These studies were supported in part by a National Heart Institute grant (H-1771), a contract with the U. S