Anti-HLA donor-specific antibodies (DSA) identified by single antigen bead array (SAB) are questioned for their excess in sensitivity and lack of event prediction after transplantation.
Population and methods: We retrospectively evaluated specific types of preformed DSA (class I, class II or C1q-fixing) and their impact on graft survival. Kidney transplantations performed across negative CDC-crossmatch were included (n=355). Anti-HLA antibodies were tested using SAB to identify DSA and their capacity to fix C1q.
Results: Twenty-eight patients with pretransplant DSA(+) with MFI>2000 were selected to assess C1q fixation. DSA were C1q+ in 15 patients and C1q- in 13, without significant differences in demographics, acute rejection, graft loss or renal function. The maximum MFI of DSA in patients with C1q-fixing DSA was significantly higher (p=0.008). Patients with DSA class-I suffered more antibody-mediated rejection (AMR) and had worse graft survival than class-II. The capacity of DSA I to fix C1q did not correlate with rejection, graft function or graft loss.
Conclusions: C1q testing in pretransplant sera with DSA was unable to predict acute antibody-mediated rejection or early graft loss, but the presence of DSA class I compared to DSA only class II did. Despite non-fixing complement in vitro, pretransplant C1q-negative DSA I can mediate rejection and graft loss.
Keywords: AMR; Antibody-mediated rejection; CDC; Complement; Complement-dependent cytotoxic; DSA; Donor-specific antibodies; Donor-specific antibody; HLA antibody; IQR; Interquartilic range; Kidney transplantation; MFI; Mean fluorescence index; SAB; Single antigen bead array.
© 2013.