Background: Banff 2013 criteria for the diagnosis of antibody-meditated rejection (AMR) in kidney transplants require the presence of donor-specific antibody (DSA). Clinical significance of histological findings of AMR in the absence of human leukocyte antigens (HLA) DSA is unclear. In recent years, our program has assumed that these cases represent AMR in which we either have been unable to identify an anti-HLA antibody by single antigen bead Luminex testing (false negative) or we were unable to identify an antibody to non-HLA molecules. Thus, we have treated most of these DSA- patients using our standard AMR protocols, although data is currently lacking. We sought to review our initial experience to assess our incidence, treatment and outcomes.

Methods: Kidney transplant (KTx) biopsies between 03/2013 and 12/2015 with histologic findings of AMR (Banff 2013) were identified.

Results: 160 KTx recipients had biopsy evidence of AMR . Of these, 139 (86.9%) were DSA+ and 21 (13.1%) were DSA-. The median time from KTx to diagnosis of DSA- AMR was 21 months (0-168 months). Median ptc+g score was 2.7 (±1.5, range 0-6) and c4d score was 0.95 (±1.24, range 0-3), with 57% (12/21) c4d negative. Mean eGFR and urine protein creatinine ratio (upc) was 25.8 (±14.4) mL/min/1.73m² and 1.5 (±2.2)gm/gm. 85.7% (18/21) of patients with DSA- AMR were treated with bolus steroids, 76.2% (16/21) with IVIG, 23.8% (5/21) with rituximab, 4.8% (1/21) with bortezomib, 14.3% (3/21) with thymoglobulin and 14.3% (3/21) received plasmapheresis. Of those treated, 15/18 had protocol follow-up biopsies demonstrating improvement of ptc+g scores (0.73+/- 0.96). The overall actuarial KTx graft survival after diagnosis of DSA – AMR was 59.2% with median follow-up of 17.2 months (0-37 months). There was no significant difference in KTx graft survival among treatment strategies or c4d status.

Conclusions: DSA- AMR is encountered less frequently than DSA+ AMR. Treatment appears to improve biopsy findings; however significant KTx graft loss occurs. More study is needed to determine the best treatment approach to DSA- AMR.

CITATION INFORMATION: Redfield R, Parajuli S, Zhong W, Astor B, Djamali A, Mandelbrot D. HLA Donor-Specific Antibody (DSA) Negative Antibody-Mediated Rejection (AMR): Incidence, Treatment and Outcomes. Am J Transplant. 2017;17 (suppl 3).

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