Summary Donor‐specific antibodies (DSA) cause antibody‐mediated rejection (AMR); however, their pathogenic role has not yet been adequately investigated after liver transplantation. The aim of our study was to analyse the clinical significance of DSA and complement‐binding DSA for the prediction of AMR after liver transplantation. Our cohort included 120 liver recipients with assessed protocol biopsies one year post‐transplant. All patients had defined HLA‐specific and complement‐binding (C1q + and C3d+) antibodies before and in regular intervals after transplantation. The incidence of DSA was evaluated in relation with clinical and histopathological data in the liver allografts. A higher occurrence of acute AMR was observed in recipients with preformed complement‐binding DSA to HLA Class I antigens. Patients who developed chronic AMR had more frequently de novo‐produced antibodies against HLA Class II antigens (P = 0.0002). A correlation was also found between de novo‐formed C1q + and C3d+‐binding antibodies to HLA Class II antigens and the development of chronic AMR (P = 0.043). Our study implies that preformed complement‐binding DSA to HLA Class I antigens are related to increased risk of acute antibody‐mediated rejection, while chronic AMR is more frequent in patients with de novo‐produced antibodies to HLA Class II antigens after liver transplantation.

The aim of our study was to evaluate the relevance of complement-binding donor-specific antibodies (DSA) for prediction of antibody-mediated rejection after liver transplantation. Sera from 123 liver transplant recipients were retrospectively defined for HLA specificity and complement-fixing activity using the single antigen beads, C1q and C3d techniques. Liver-recipients´ sera were tested before transplantation, 3, 6 months and one year after transplantation. Patients were followed up for graft survival and rejection incidence for one year after transplantation. All patients with pre-transplant complement-binding DSA developed severe antibody-mediated rejection after transplantation, while three recipients out of four, who produced de novo complement-fixing DSA, developed AMR. Definition of DSA with respect to complement-fixing activity may provide clinically relevant information about the risk of antibody-mediated rejection after liver transplantation This article is protected by copyright. All rights reserved.