Renal pathology in the pediatric transplant patient.

Renal transplantation is a therapeutic goal for children with advanced chronic kidney disease. There are many causes of renal dysfunction in children with allografts--the transplanted kidney can develop a variety of morphologic alterations leading to dysfunction. Evaluation of the kidney biopsy is one of the best methods of determining the cause of graft dysfunction. Rejection is a major cause of renal allograft failure in children. The morphologic hallmarks of acute antibody-mediated and cell-mediated rejection and chronic allograft nephropathy have been codified in classification strategies that are useful in adults and children. Viral infection and Epstein-Barr virus-driven posttransplant lymphoproliferative disease also occur in the pediatric transplanted kidney. Drug toxicity from immunosuppressive agents also causes characteristic morphologic alterations in the renal allograft. As the survival of pediatric heart and liver transplant patients improves, the incidence of immunosuppression therapy-related disease in the native kidney in these patients will likely become more important clinically. In addition to renal lesions related to the allograft state, glomerular disease can recur or occur de novo in renal allografts. Here, we describe the pathology of the more common morphologic lesions in kidneys of children with a renal allograft.

Early renal benefit of rapamycin combined with reduced calcineurin inhibitor dose in pediatric heart transplantation patients.

BACKGROUND: Calcineurin inhibitors such as cyclosporine are effective in preventing rejection in recipients of solid organ transplants. Unfortunately, the prolonged use of calcineurin inhibitors may result in progressive renal injury. METHODS: We studied the renal function of 15 pediatric heart transplant recipients who were taking calcineurin inhibitors. Their renal function was studied before and after rapamycin was introduced to their immunosuppression regimen. With the introduction of rapamycin, the patients were given a lower dose of calcineurin inhibitors, and the calcineurin inhibitor was discontinued in 5 patients. RESULTS: Renal function improved significantly in the patients by 30 days after these changes in the calcineurin inhibitor dose were instituted. Mean levels of blood urea nitrogen and mean serum creatinine decreased, and mean creatinine clearance increased. Pre-rapamycin, the patients' mean level of blood urea nitrogen was 27.1 +/- 12.4 mg/dl and post-rapamycin they decreased to 18.6 +/- 11.1 mg/dl (p = 0.014). Similarly, creatinine decreased from 1.0 +/- 0.5 mg/dl to 0.8 +/- 0.3 mg/dl (p = 0.019). Their creatinine clearance increased from 88 +/- 28 ml/min/1.73 mol/liter2 to 105 +/- 27 ml/min/1.73 mol/liter2 (p = 0.008). The patients' lipid levels did not change after they were prescribed rapamycin. Biopsy-negative rejection developed in 2 patients. CONCLUSIONS: The introduction of rapamycin to the immunosuppressive regimen of patients taking calcineurin inhibitors, with a concomitant reduction of the calcineurin inhibitor dose, may improve renal function within 30 days, without a significant increase in rejection.