Transplantation Tolerance— The Search Continues

Abstract

The induction in a host of immunologic tolerance to the major histocompatibility complex (MHC) antigens of a donor (in humans, the HLA antigens) is the unquestioned goal of clinical transplantation. This goal is critical because the strength and diversity of the host's immune responses to the donor's MHC antigens have long been recognized as the principal cause of allograft rejection. Indeed, the MHC system was initially identified by its association with rejection in transplantation studies in animals more than 50 years ago,¹ and it is now recognized for its key role in orchestrating the immune responses to all antigens.The . . .