ABSTRACT
All viable human tissue transplants from one individual to another are at risk of rejection. The extent of risk depends on the donor-host disparity for genetic products coded by HLA and non-HLA genes. Tissues vary widely in their susceptibility to rejection. Thus, unrelated donor marrow transplants are exquisitely sensitive to single mismatches for HLA, whereas 90% of corneal transplant recipients tolerate ABO and HLA mismatched grafts well. In cornea and marrow transplantation, immunosuppression can be safely withdrawn once inflammatory responses have settled down. In other transplants including kidneys, hearts, lungs, and livers immunosuppression is necessary for the lifetime of the transplant, thus, adaptation processes vary between organs and tissues. The relationship between availability of donors and proportion of patients who could achieve a beneficially matched organ transplant was investigated in a simulation model.
