No Association of Kidney Graft Loss With Human Leukocyte Antigen Antibodies Detected Exclusively by Sensitive Luminex Single-Antigen Testing: A Collaborative Transplant Study Report

Background. It is unclear whether kidney transplant recipients with preformed donor-specific human leukocyte antigen (HLA) antibodies (DSA) detectable only in the highly sensitive Luminex single-antigen (LSA) assay are at an increased risk of graft failure. Methods. We studied 3148 patients who received a deceased donor kidney graft between 1996 and 2008 and were enrolled in the prospective serum project of the Collaborative Transplant Study. There were 118 patients with graft loss during the first 3 years after transplantation on whom recipient and donor DNA was available for complete HLA typing. We compared the incidence of LSA-detected DSA in these patients with graft failure and matched controls with functioning grafts. All patients were found negative in the less-sensitive complement-dependent lymphocytotoxicity and enzyme-linked immunosorbent assays. Results. When mean fluorescence intensity (MFI) of greater than or equal to 1000 was used as a cutoff for Luminex positivity, 118 patients with graft loss did not show a higher incidence of DSA against HLA-A, -B, -C, -DRB1/3/4/5, -DQA1, -DQB1, -DPA1, or -DPB1 antigens than 118 matched controls without graft loss (for all loci P not significant). The incidence of strong DSA(MFI >= 2000 or MFI >= 3000) detected only by LSA was low (for all loci between 0% and 5%) and did not identify unacceptable antigens that were relevant for graft loss within the first 3 years after transplantation. Conclusion. We conclude that, given currently practiced crossmatch procedures and immunosuppressive regimens, exclusion of donor organs carrying "unacceptable" HLA based exclusively on sensitive LSA antibody testing is not justified.