Kidney transplant recipients with DSA have a greater likelihood of developing antibody-mediated rejection (ABMR) and kidney allograft loss. The aim of this study was to investigate whether SAFB determination of serum DSA (sDSA) MFI with or without serum pre-treatment with EDTA, the DSA ability to bind C1q or C3d, or the intra-graft detection of DSA (gDSA) at the time of the transplant biopsy have clinical utility for predicting ABMR and kidney allograft survival.

77 kidney transplant recipients with a graft biopsy and sDSA were included. gDSA were identified after an acid elution from biopsy samples. The C1q and C3d assays were performed in laboratories with expertise in these assays.

The median time between transplantation and biopsy was 25 months (range: 0.5-251), and the median follow-up was 24 months (range 0-125). EDTA-treatment of serum improved the prediction of a positive result for both the C1q and C3d assays (p=0.01 for C1q andp=0.007 for C3d) but not for gDSA assay (p=0.4). An EDTA MFI over 3844 predicted a positive C1q assay with a sensitivity of 87% and specificity of 93.5%. An EDTA MFI over 3898 predicted a positive C3d assay with a sensitivity of 88.1% and a specificity of 88%. 40.3% of biopsy specimens were in favor of ABMR. The sensitivity and specificity of the C1q assay for predicting ABMR were 67% and 61%, respectively. The sensitivity and specificity of the C3d assay for predicting ABMR were 52% and 69%, respectively. In univariate analysis, sDSA noEDTA MFI >2500, sDSA EDTA MFI >3800, C3d+ DSA and gDSA were associated with death-censored graft loss, while C1q+ DSA was not. Using 4 multivariate models, the independent factors associated with death-censored graft loss were estimated-GFR, ci+ct score, and C4d positivity.

In conclusion, eGFR and histopathologic criteria of humoral rejection are the best prognosis factors for subsequent graft loss. Our findings weaken the rational of implementing any of the C1q, C3d or gDSA assays to the clinical practice because they do not predict independently ABMR and graft loss at the time of the biopsy.

CITATION INFORMATION: Couzi L, Courant M, Visentin J, Dubois V, Lepreux S, Guidicelli G, Thaunat O, Merville P, Taupin J.-L. Poor Prediction of Rejection and Kidney Survival by Donor-Specific-Antibodies Characterization. Am J Transplant. 2017;17 (suppl 3).

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