Kidney transplant rejection
Kidney transplant rejection is a serious complication following kidney transplantion which may lead to graft loss. We distinguish several types.
Early complications following kidney transplantation
Acute renal allograft rejection is a severe complication of kidney transplantation. Thanks to modern immunosuppressant drugs and induction regimens there has been a considerable reduction in acute rejections in the past decades. Acute rejection is defined as an acute reduction in organ function (usually seen as a creatinine increase) with specific pathological changes in the graft. Most cases occur within the first six months after transplant, with many cases occurring early after surgery.
There are two major types, acute T-cell mediated rejection and acute antibody-mediated rejection. There may be a mix of the two.
Luckily, the success rate of therapy for acute rejection is over 90%.
Clinical features
Acute rejection is mostly asymptomatic, as secondary hypertension, proteinuria, and creatinine increase are the most common findings. However, patients may also have features of acute kidney injury.
Diagnosis
Diagnosis requires renal biopsy. The severity is graded according to the histological Banff classification. It ranges from mild (I/A, II/A) to severe (II/B, III/B).
Treatment
Acute rejection is treated with more aggressive immunosuppressants, usually high-dose corticosteroids with or without antithymocyte globulin (ATG). If antibody-mediated, plasmapheresis may be used as well.
Prevention
Preventing acute rejection is essential and the most important reason why good compliance regarding taking the immunosuppressants is so important for transplant patients. It’s also important to ensure enough fluid intake, screening patients regularly, and educating patients on symptoms to watch out for.
Late complications following kidney transplantation
Chronic allograft nephropathy is a pathological diagnosis corresponding to so-called chronic or late transplant rejection. It causes interstitial fibrosis and tubular atrophy, which causes chronic allograft dysfunction, usually seen as a slow, progressive decrease in kidney function. It may develop at any time after transplant, even after years.
Risk factors include acute rejection, incomplete immunological compatibility, as well as other risk factors for renal disease like hypertension, obesity, etc.
Treatment
There is no effective therapy for late rejection, and all patients inevitably progress to end-stage kidney disease. However, calcineurin inhibitors like tacrolimus are nephrotoxic, and so reduction of tacrolimus is often tried in an attempt to slow the progression. Any concomitant kidney disease should be treated, and renal risk factors should be reduced.