Therapeutic Apheresis in Pediatric Renal Transplant Recipients

Clear guidelines for therapeutic apheresis in children after renal transplant do not exist. This article reviews the current experiences with therapeutic apheresis in pediatric transplant recipients. The ideal characteristics of removable substances should have all of the following criteria for an effective therapeutic apheresis: large molecular weight (>15 kDa), prolonged half-life, rapid elimination from the plasma, high intravascular distribution, and low turnover rate. Among these molecules, immunoglobulin M is ~75% intravascular; thus, only 1 or 2 therapeutic apheresis procedures are needed to reduce immunoglobulin M levels efficiently. In contrast, immunoglobulin G is distributed 45% intravascularly and returns to ~60% of preapheresis level within 48 hours; thus, the regimen involves 5 procedures and immunosuppressive therapy is crucial to reduce immunoglobulin G levels. Therapeutic apheresis can also remove cytokines. Immunomodulatory effects of therapeutic apheresis do not only remove unwanted substances but involve other important mechanisms, including increased T-regulatory cells compared with T-effector cells. Many modalities of therapeutic apheresis are used for pediatric transplant recipients, including plasmapheresis, double filtration plasmapheresis, photopheresis, lipopheresis, and immunoadsorption, which is the most effective but has a high cost. Therapeutic apheresis in pediatric transplant recipients is effective for posttransplant nephrotic syndrome (mainly focal segmental glomerulosclerosis). Therapeutic apheresis has also resulted in partial or complete remission for 66% of patients with atypical hemolytic uremic syndrome and 75% response rate for chronic antibody-mediated rejection. However, therapeutic apheresis should be accompanied by other immunosuppressive drugs to prevent rebound phenomena. Potential complications of therapeutic apheresis in pediatric transplant recipients include fluid and electrolyte imbalances, infection, bleeding, and reactions to replacement fluids during therapeutic apheresis. However, therapeutic apheresis (combined with immunosuppression) is an effective tool in most pediatric renal transplant recipients for management of antibody-mediated rejection, focal segmental glomerulosclerosis, and atypical hemolytic uremic syndrome.