RT Journal Article T1 Impact of Preformed Donor-Specific Anti-Human Leukocyte Antigen Antibody C1q-Binding Ability on Kidney Allograft Outcome. A1 Molina, Juan A1 Navas, Ana A1 Agüera, Maria-Luisa A1 Rodelo-Haad, Cristian A1 Alonso, Corona A1 Rodriguez-Benot, Alberto A1 Aljama, Pedro A1 Solana, Rafael K1 C1q-binding antibodies K1 Allograft-loss risk K1 Kidney allograft survival K1 Kidney transplantation K1 Preformed anti-HLA antibodies K1 Single antigen beads assay AB The consolidation of single antigen beads (SAB-panIgG) assay in the detection of preformed anti-human leukocyte antigen (HLA) antibodies has improved transplantation success. However, its high sensitivity has limited the allograft allocation for sensitized patients, increasing their waiting time. A modification of the standard SAB-panIgG assay allows the detection of that subset of antibodies capable of binding C1q (SAB-C1q assay). However, the clinical usefulness of SAB-C1q assay for determining the unacceptable mismatches is under discussion. We retrospectively analyzed the impact of preformed donor-specific anti-HLA antibodies (DSA) according to the C1q-binding ability on allograft outcome, examining 389 single-kidney transplanted patients from deceased donors. Recipients with preformed C1q-binding DSA showed the lowest allograft survival up to 7 years (40.7%) compared to patients with preformed non-C1q-binding DSA (73.4%; p = 0.001) and without DSA (79.1%; p < 0.001). Allograft survival rate was similar between patients with preformed non-C1q-binding DSA and patients without preformed DSA (p = 0.403). Interestingly, among the high-mean fluorescence intensity DSA (≥10,000) population (n = 46), those patients whose DSA were further capable of binding C1q showed a poorer allograft outcome (38.4 vs. 68.9%; p = 0.041). Moreover, in our multivariate predictive model for assessing the risk of allograft loss, the presence of C1q-binding DSA (HR 4.012; CI 95% 2.326–6.919; p < 0.001) but not of non-C1qbinding DSA (HR 1.389; CI 95% 0.784–2.461; p = 0.260) remained an independent predictor after stratifying the DSA population according to the C1q-binding ability and adjusting the model for other pre-transplantation predictive factors including donor age, cold-ischemia time, and HLA-DR mismatches. In conclusion, the unacceptable mismatch definition according to the SAB-C1q assay would improve the risk stratification of allograft loss and increase the limited allograft allocation of highly sensitized patients, shortening their waiting time. PB Frontiers Research Foundation SN 1664-3224 YR 2017 FD 2017-09-29 LK http://hdl.handle.net/10668/11829 UL http://hdl.handle.net/10668/11829 LA en NO Molina J, Navas A, Agüera ML, Rodelo-Haad C, Alonso C, Rodríguez-Benot A, et al. Impact of Preformed Donor-Specific Anti-Human Leukocyte Antigen Antibody C1q-Binding Ability on Kidney Allograft Outcome. Front Immunol. 2017 Oct 31;8:1310. NO The publication of this work was co-financed by the PI16/01615 (to RS) from the Spanish Ministry of Health (Instituto de Salud Carlos III) and by European Regional Development Funds (FEDER). DS RISalud RD Apr 18, 2025