Kidney allograft tolerance in diabetic patients after total lymphoid irradiation (TLI)

The value of total lymphoid irradiation (TLI) combined with low dose prednisone as sole immunosuppressive regimen in renal allograft transplantation in humans has been investigated. Seventeen patients with end-stage diabetic nephropathy received TLI to a cumulative dose of 20-30 Gy in fractions of 1 Gy. Cadaver kidneys were grafted as soon as they were available after completion of TLI. Low dose prednisone was given after transplantation. Profound and long-term immunosuppression has been achieved in all patients. Six patients live already more than one year (greater than 2 years in 3 of them) and 7 for less than one year with a functioning kidney graft. Two out of these 13 patients had repeated rejection episodes necessitating a supplementary immunosuppressive treatment with cyclosporine A. One patient returned to chronic hemodialysis 11 months after transplantation and died of pericardial tamponade one month later. One patient had severe acute rejection for which cyclosporine A was administered; he died of septic shock as a consequence of immune deficiency a month later. The other two patients succumbed to other causes (myocardial infarction and hyperglycemia). The amount of steroids and azathioprine administered to these patients was substantially lower than in the case of conventional immunosuppression. The preliminary results are thus encouraging. However, the treatment schedule as used in the present study can not yet be considered as optimal since the majority of patients still had one or more rejection episodes. Further investigations are warranted. The optimal dose of radiation, the importance of the interval between TLI and organ transplantation, the influence of splenectomy on the immunity, etc., are still to be assessed.