Rejection of the kidney allograft.

Copyright © 2010 Massachusetts Medical Society. The science of kidney transplantation has progressed considerably in the past half-century largely because of an improved understanding of the role of the immune system in allograft rejection, the disentanglement of the molecular mechanisms underlying graft failure, and better management of immunosuppression.1,2 Rejection has always been the major obstacle. Transplantation of tissues or cells from a donor who differs genetically from the graft recipient induces an immune response in the recipient against alloantigens of the donor graft. If not controlled, this response will destroy the graft. Recent discoveries have clarified how T lymphocytes, the principal agents of acute rejection, travel to and recognize the allograft. Important progress has also been made in understanding the influences of costimulatory molecules and cytokines and in elucidating how the innate immune system participates in graft rejection. In this review, we discuss the mechanisms underlying renal allograft rejection in the order of their clinical occurrence after transplantation.