The results of HLA-incompatible kidney transplantation according to pre-transplant crossmatch tests: Donor-specific antibody as a prominent predictor of acute rejection.

Background: Crossmatching (XM) between organ donors and recipients is correlated with clinical outcomes. This study evaluates the results of HLA-incompatible kidney transplant (HLA-i KT) according to pre-transplant XM modalities.

Methods: This study included 731 consecutive patients. HLA-i KT was defined as a transplant under conditions of complement-dependent cytotoxicity (CDC) XM positivity, flow-cytometric XM (FCXM) positivity, and/or maximal donor-specific antibody (DSA) mean fluorescence intensity (MFI) ≥5000.

Results: The incidence of antibody-mediated rejection (AMR) within 1 year after transplant was significantly higher in the HLA-i group than in the HLA compatible (HLA-c) group (15 vs 9 patients, 14.2% vs 1.4%; P < 0.01). Multivariate analysis indicated that a DSA MFI ≥5000 (odds ratio [OR] = 2.63; 95% confidence interval [CI], 1.00-6.98; P = 0.05) was significantly associated with acute rejection (AR), whereas CDC (OR = 2.09; 95% CI, 0.55-7.99; P = 0.28) and FCXM positivity (OR = 2.07; 95% CI, 0.73-5.87; P = 0.17) were not. Similarly, DSA MFI ≥ 5000 (OR = 4.14; P = 0.02) was the only significant factor affecting the risk of AMR.

Conclusions: Of the various XM tests, DSA MFI ≥5000 was the most prominent predictor of AR in patients undergoing HLA-i KT.