369 Therapeutic Plasma Exchange in Small-Bowel Transplant Recipients With Acute Allograft Rejection

Abstract

Therapeutic plasma exchange (TPE) is used in solid-organ transplant patients to treat antibody-mediated rejection (AMR) by removing donor specific antibodies (DSAs). While ASFA guidelines exist for treating AMR in other solid-organ transplants, no such guidelines exist for small bowel-allograft patients; the benefit of TPE in AMR of small bowel transplant patients has not been studied. Five patients were followed with serial surveillance ileoscopies and allograft biopsies. Tissues were processed using standard protocols (UNMC) for permanent histologic examination. Two H&E stained slides from each biopsy were examined microscopically by gastrointestinal/transplant pathologists for evidence of ACR. To assess for AMR, serial serum DSA levels were obtained via by Luminex LabScreen single antigen bead assay (One Lambda, Canoga Park, CA). Patients were treated with at least five TPE procedures. To determine whether TPE provided benefit, we examined three parameters in the post-apheresis period: DSA presence and strength, histopathologic rejection, and clinical response. All patients developed class I and/or class II DSAs following transplant. No clear change in DSA levels following TPE was seen. Sixty percent of patients (3/5) had histopathologic evidence of acute cellular rejection (ACR) prior to initiation of TPE. Following TPE, biopsies showed no evidence of ACR or did not meet the criteria necessary for evaluation. Management of rejection in small bowel transplant patients, caused by both antibody-mediated and T-cell driven processes, is extremely complex. We examined the impact of performing TPE in patients with histologic and/or clinical evidence of acute rejection. A clear trend in the burden or activity of DSAs, histopathologic improvement of allograft biopsies, or clinical improvement following administration of TPE, was not seen. Thus, in our study, TPE does not appear to have a clear benefit in the treatment of AMR and/or ACR in small bowel rejection. Additional studies will be needed to corroborate our results.