The prospects for xenotransplantation of the kidney

A severe shortage of transplant donors has led to a markedly prolonged waiting time for renal transplantation and has thus sparked interest in the use of animals in lieu of humans as a source of kidneys for transplantation. Clinical application of xenotransplantation is limited in large part by the severe immunologic reaction of the recipient against the graft. This immunologic reaction is mediated initially by components of natural immunity, such as xenoreactive antibodies, complement and natural killer cells, and later by elicited humoral and cellular immune responses that act in concert to disrupt the function of the endothelial lining of blood vessels. The past few years have brought considerable progress in elucidating the molecular and cellular basis of xenograft rejection and in developing strategies to overcome it.