 Following transplantation, recipients of organ allografts are placed on immunosuppression indefinitely. Despite dramatic improvements in acute rejection rates and short-term graft survival, long term graft survival has not changed appreciably over the past 20 years. In kidney transplantation, the leading cause of late graft loss is chronic allograft nephropathy CAN. This disorder is clinically characterized by a progressive decline in kidney function, associated with the characteristic histologic features of interstitial fibrosis and inflammation, arteriosclerosis, glomerulosclerosis, and tubular atrophy. Both immunologic and non-immunologic factors have been implicated in the development of CAN. However, the etiology of this disorder has not been clearly defined nor is there specific therapy for treating CAN. 