Impact of pretransplant donor‐specific antibodies on kidney allograft recipients with negative flow cytometry cross‐matches

The Luminex test can detect low levels of donor‐specific antibody ( DSA ) that cannot be detected by flow‐cytometric cross‐matching ( FCXM ) in kidney transplantation ( KT ). This study evaluated the impact of DSA on clinical outcomes in KT recipients negative on FCXM . Of 575 consecutive patients who underwent living donor KT between January 2013 and July 2016, 494 (85.9%) were DSA ‐negative and 81 (14.1%) were DSA ‐positive. Although rates of acute cellular rejection ( ACR ) at 1 year were similar in the 2 groups ( P  =   .54), the incidence of antibody‐mediated rejection ( ABMR ) was significantly higher in the DSA ‐positive group ( P  <   .01). There was no statistically significant association between rejection‐free graft survival ( RFGS ) rates and pretransplant class I DSA . However, evaluation of pretransplant class II DSA showed that RFGS rates were significantly lower in patients with mean fluorescence intensity ( MFI ) >3000 than in patients with DSA ‐negative ( P  <   .01). On multivariate analyses, class II DSA MFI ≥5000 was a significant risk factor for acute rejection (hazard ratio, 7.48; P <  .01). These findings suggested that pretransplant DSA alone did not affect graft survival in KT recipients without desensitization. However, class II DSA MFI >5000 was an independent predictor of acute rejection in DSA ‐positive patients.