What the Clinician Should Know About the Major Histocompatibility Complex

THE MAJOR histocompatibility complex (MHC) is a closely linked group of genes that provide the code for the structure of cell surface antigens and several plasma proteins, as well as for factors that regulate immune responses to a variety of antigens. The MHC plays a major role in tissue transplantation and in a wide variety of diseases in man. Because of its important relationships to clinical medicine and because of a number of unique properties of the MHC itself, this group of genes has received an enormous amount of attention in recent years. This is underscored by the fact that the Nobel Prize in Medicine and Physiology this year was awarded to three investigators (Drs Baruj Benacerraf, Jean Dausset, and George Snell) for work related to the MHC. It is the purpose of this brief review to outline major aspects of the MHC in man and experimental animals and to