Marta Crespo, Alberto Torio, Virginia Mas, Dolores Redondo, Maria J.Pérez-Sáez, Marisa Mir, Anna Faura, Rita Guerra, Olga Montes-Ares, Maria D.Checa, Julio Pascual
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 C1qfixing) and their impact on graft survival. Kidney transplantations performed across negative CDC-crossmatch were included (n = 355). Anti-HLA antibodieswere tested using SAB to identify DSA and their capacity to fix C1q.
Results: Twenty-eight patients with pretransplant DSA+ with MFI N 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 serawith 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: Antibody-mediated rejection, Complement, Donor-specific antibody, HLA antibody, Kidney transplantation
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