Transplant immunology I: immunological mechanisms of graft injury

Graft injury following solid-organ transplantation and leading to rejection is mediated by innate (early and non-specific) and acquired (rapid response to antigen) immunological mechanisms. Hyperacute rejection is rare and minimized by applying a leukocyte crossmatch test at harvest. Acute rejection occurs within days to weeks of transplant. Major histocompatibility complex (MHC) molecules have a role in activating T-cells against foreign antigen which is presented on leukocytes called professional antigen-presenting cells (APCs). Co-stimulatory molecules are also required. The role of cluster of differentiation-4+ (CD4+) T-cells in allorecognition is discussed. CD8+ T-cells probably contribute to graft damage.