ABSTRACT
This chapter discusses in three main areas of transplantation immunobiology. First is the alloantigen, their definition in strong and weak systems. Second is the genetic organization of the major histocompatibility complex. Finally the effector mechanisms in transplantation: cells and antibodies. Research in the field of transplantation of tissues and organs is now very active in areas which parallel the prior developments in blood banking. One possibility is that antigens cross-reactive to major transplantation antigens are widely present in nature and that environmental exposure, such as to bacteria of the gastrointestinal tract, may constantly stimulate a response resulting in production of large numbers of cross-reactive "memory" cells. Performance of a cross-match of recipient serum against donor lymphocytes has become a routine procedure prior to transplantation and has greatly reduced the incidence of the early "hyperacute" vasculitis which usually occurs when such a transplant is performed, a situation analogous to the transfusion of ABO incompatible blood.
