Significance of low-level DSA detected by solid-phase assay in association with acute and chronic antibody-mediated rejection.

We sought to clarify the controversial issue of whether detecting low-level anti-donor-specific HLA antibody (HLA-DSA) by single-antigen flow-bead assay (SAFB) may have a potential role in reducing acute and chronic antibody-mediated rejection (AMR). We retrospectively studied the preoperative serum of ABO-compatible living kidney transplantation recipients transplanted between 2001 and 2004 by SAFB using a Luminex platform. HLA-DSA was detected only by SAFB in 24 patients, although all of them showed negative T-cell and B-cell complement-dependent cytotoxicity (CDC) crossmatches. The HLA-DSA patients went on to have surprisingly high levels of acute and chronic AMR despite being only weakly sensitized (acute AMR, 33.3%; chronic AMR, 41.7%). After 2005, we implemented SAFB routinely and any patient having a positive HLA-DSA was considered to be a desensitization candidate. The 52 patients found to have HLA-DSA underwent kidney transplantation after prior treatment with a single dose of rituximab (RIT) and three or four sessions of double-filtration plasmapheresis (DFPP) in addition to regimens commonly used between 2001 and 2004. After 2005, there was a significant reduction in the occurrence of acute and chronic AMR (acute AMR, 4.7%, P < 0.001; chronic AMR, 4.7%, P < 0.001). The 5-year graft survival rate also improved after implementing SAFB (83.3-98.1%, P = 0.032). The RIT/DFPP-induction protocol may improve graft survival even in patients with low-level DSA.