REMOVAL OF LYMPHOCYTOTOXIC ANTIBODIES BY PRETRANSPLANT IMMUNOADSORPTION THERAPY IN HIGHLY SENSITIZED RENAL TRANSPLANT RECIPIENTS

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Abstract
A high level of panel-reactive antibodies (PRA) in potential renal transplant recipients is associated with a long waiting time until transplantation and correlates inversely with graft outcome. We report our experience with the employment of immunoadsorption (IA) using a column composed to sepharose-bound staphylococcal protein A (which has a relatively selective affinity for binding IgG compared with other immunoglobulins) to decrease the PRA levels and expedite transplantation in 6 highly sensitized potential renal transplant recipients (1 primary and 5 awaiting second transplants). All patients had PRA levels of greater than or equal to 70% for a duration of 1 year prior to IA. Only patients with antibody specificity localized to 1 or 2 HLA A or B antigens were accepted for the study. IA procedures were performed on alternate days until a twofold decrease in antibody titer had occurred (maximum: 6 procedures). Repeat procedures were initiated if the HLA antibody titer returned to its baseline value. Intravenous cyclophosphamide (CY) (10 mg/kg/day every 3 weeks) and methylprednisolone (MP) (0.5 mg/kg/day) were provided as adjunctive immunosuppression until transplantation. A total of 44 immunoadsorption procedures were performed (27 primary and 17 repeat) with treatment of 2.49 +/- 0.02 plasma volumes per session. Serum IgG concentration decreased 95 +/- 3% and PRA activity decreased 75 +/- 16% after the primary treatment course. Four patients received cadaveric grafts within 3.7 +/- 1.2 months following the last IA procedure. Three grafts are functioning at 1 year, 8 months, and 8 weeks posttransplant. The remaining graft demonstrated primary nonfunction. All four patients had a past positive crossmatch using pre-IA sera with their respective donors. Patients not transplanted exhibited rapid resynthesis of IgG and a return of the PRA towards baseline levels within a few weeks after IA. We conclude that IA can effectively remove HLA antibodies and expedite graft availability in highly sensitized patients.