Significance of Pretransplant False Positive Lymphocytotoxic Crossmatch in Liver Transplant Recipients

Abstract

Purpose: At the time of transplantation, the recipient serum is tested with the prospective donor lymphocytes to identify specific reactivity in the donor-specific crossmatch. A positive crossmatch is a contraindication for kidney transplantation because of the higher incidence of antibody mediated rejection. However, numerous studies has found that the liver is resistant to it. We investigated the relationship between the pretransplant lymphocytotoxic crossmatch results and the long-term outcome after liver transplantation in a single center. Methods: From January 1996 to December 2010, 1021 living or deceased donor liver transplant recipients were included. Their medical records and pretransplant crossmatch results were collected. Results: 69 of 1021 (6.8%) liver transplants were performed with a positive crossmatch and their outcome was compared with the remaining 952 performed with a negative crossmatch. No significant differences in rejection, biliary complication, vascular complication, primary disease recurrence and de novo malignancy were found in negative and positive T- or B-lymphocytotoxic crossmatch recipients. Graft loss and patient survival were not inferior in the recipient group testing positive crossmatch. Besides, T and B cell crossmatch against donor showed positive results initially. But recipient's autocontrol (recipient's cell + recipient's serum) also showed similar positive results. After dithiothreitol(DTT) treatment, all previous positive result was converted to negative. So, IgM class autoantibody against recipient's own antigen was strongly suggested. We defined these subpopulation as false positive crossmatch group, accounting for 41 (4.0%) recipients. Significantly high incidences of de novo malignancies, especially lymphoid malignancy including posttransplant lymphoproliferative disorder, were observed in false positive crossmatch recipients compared to those of negative controls. (P=0.018 in overall de novo malignancy, p=0.029 in lymphoid malignancy) Conclusion: This study demonstrated that the presence of circulating IgM autoantibody in the recipient may be a risk factor for de novo malignancy, specially lymphoid malignancy. Although the precise mechanism remains unclear, immunologic factors is considered to involve in the pathogenesis of de novo malignancy.