Calcineurin inhibitor-free immunosuppression in renal allograft recipients with thrombotic microangiopathy/hemolytic uremic syndrome.

Thrombotic microangiopathy (TMA) and hemolytic uremic syndrome (HUS) represent serious threats to kidney allograft recipients. During a 4-year period, among 850 kidney transplantations, seven recipients with primary HUS and seven recipients (eight transplants) with previous or de novo TMA/HUS were identified and given calcineurin inhibitor (CNI)-free immunosuppression by sirolimus (SRL), mycophenolate mofetil and steroids. Thirteen out of 15 transplantations were successful in the long term; resulting in a mean creatinine of 101 mumol/L (16.4 months follow-up). In patients maintained on CNI-free regimen, no TMA/HUS recurrences were observed. A high rate of acute rejections (53%) may indicate insufficient immunosuppressive power and/or a causative relationship between TMA/HUS and rejection. Wound-related complications were abundant (60%), and call for surgical/immunosuppressive countermeasures. Our experience supports the idea that CNI's are major offenders in TMA/HUS induction. Total CNI elimination seems essential, as the nephrotoxic combination CNI + SRL may promote TMA. Features of TMA/HUS should be carefully explored in recurrent 'high responders'.