Because early humoral graft rejection is considered to be complement mediated, this SAB-based technique may provide a valuable tool in the pretransplant risk stratification of kidney transplant recipients. Methods Previously, we established that pretransplant donor-specific Alvimopan monohydrate anti-HLA antibodies (DSAs) are associated with increased risk for long-term graft failure in complement-dependent cytotoxicity crossmatch-negative transplants. patients with C3d-fixing antibodies had a death-censored, covariate-adjusted graft survival of 60%, whereas patients with nonCC3d-fixing DSA had a graft survival of 64% (hazard ratio, 1.02; 95% confidence interval, 0.70 to 1 1.48 for C3d-fixing DSA compared with nonCC3d-fixing DSA; Valuetest for continuous variables. bChi-squared test for categorical variables. cT cellCdepleting antibody therapy: ALG, ATG, OKT3 mAb. The AKME showed 10-12 months death-censored graft survival rates of 78% (95% CI, 74% to 81%) for the 4157 patients without DSA, 64% (95% CI, 62% to 66%) for the 470 of 567 patients with nonCC3d-fixing DSA, and 60% (95% CI, 49% to 70%) for the 97 patients with C3d-fixing DSA in pretransplant serum (Physique 2A). The multivariable analysis, also adjusted for the same covariables, showed that the risk of graft failure was comparable for C3d-fixing and nonCC3d-fixing DSA (HR, 1.02; 95% CI, 0.70 to 1 1.48 for C3d-fixing DSA compared with nonCC3d-fixing DSA; complement-fixing antibodies, as detected by SAB C1q or C3d assays, on graft survival has not been shown so far. In contrast, several studies showed a negative effect on graft survival of DSA, mostly found at the time of a rejection episode.14C17 Loupy DSA in pediatric kidney transplantations revealed that C3d-fixing DSA (and not C1q-fixing DSA) was associated with decreased kidney function after transplantation.16 At the time of detection of DSA, the 5-12 months kidney graft survival was shown to be significantly lower when DSAs were C3d fixing, especially if the Alvimopan monohydrate C3d-fixing DSAs were detected against both HLA classes 1 and 2 antigens.17 In comparison with all published studies that used the Lifecodes C3d assay to determine C3d-fixing DSA in patients with kidney transplants, we found a lower percentage of patients who were C3d positive. This difference could be due to patient selection, time of serum sample, and/or IgG DSA positivity cutoff (Supplemental Table 2). There might be a difference in the effect of C3d-fixing DSA pretransplant versus post-transplant, because DSAs seem to be more detrimental, and if these are also C3d fixing, this might increase the risk of graft failure. Detection of C3d may be a more valid reflection of complement activation compared with detection of C1q, because C3d Alvimopan monohydrate is positioned downstream in the complement cascade. However, there are multiple factors that regulate complement activation: antigen expression and density, antibody titer, avidity, subclass, glycosylation, and local complement concentration.18 In addition, the prevalence of C3d-fixing DSA may be higher post-transplant compared with pretransplant. Others have shown that post-transplant C3d-fixing DSAs are associated with increased risk of graft failure. Although we have analyzed pretransplant sera for the presence of C3d-fixing DSA in a much larger cohort compared with previous studies, our findings do not indicate that the C3d-binding status Alvimopan monohydrate of DSA at the time of transplantation can contribute to risk stratification of renal transplant recipients. Disclosures None. Supplementary Material Supplemental Data: Click Alvimopan monohydrate here to view. Acknowledgments This study was supported by research funding from Dutch Kidney Foundation project code CP12.23 (risk assessment of kidney graft failure PDPN by HLA antibody profiling). Footnotes Published online ahead of print. Publication date available at www.jasn.org. This article contains supplemental material online at http://jasn.asnjournals.org/lookup/suppl/doi:10.1681/ASN.2018020205/-/DCSupplemental..