Cardiac transplantation: immune mechanisms and alloantigens involved in graft rejection.

Recent advances in surgical and chemotherapeutic approaches to cardiac transplantation have resulted in substantial improvements in patient survival. Rejection of the cardiac allograft by the recipient's immune system and complications associated with immunosuppressive therapy remain, however, important clinical problems. The rejection of the transplanted heart is a complex set of immunological reactions. Previous experimental work has indicated that a variety of mechanisms may be involved in the pathogenesis of heart rejection; these include alloantibodies, specifically sensitized cytotoxic T-lymphocytes, lymphokine-dependent T-lymphocyte delayed-type hypersensitivity reactions, and natural killer cells. The current knowledge of the role that genetic incompatibilities play in stimulating the cardiac allograft reaction and the effector mechanisms implicated in the pathogenesis of the rejection process will be discussed.