Increased negative impact of donor HLA-specific together with non-HLA-specific antibodies on graft outcome

BACKGROUND: De novo donor HLA-specific (dnDSA) and non-HLA antibodies including antiangiotensin type 1 receptor antibodies (AT1R-abs) have been associated with antibody-mediated rejection (AMR) and decreased graft survival as well as cellular-mediated rejection (CMR) and early onset of microvasculopathy in heart transplantation. The aim of our study was to determine the impact of anti-AT1R-ab and anti-donor HLA-specific antibody (DSA) on clinical outcomes. METHODS: Pretransplant and posttransplant sera from 200 recipients transplanted between May 2007 and August 2011 were tested for DSA (Luminex-based single antigen bead assay) and AT1R-ab (enzyme-linked immunosorbent assay). Two cutoff levels (≥17 and ≥12 units) were used to define high and intermediate binding of AT1R-ab. Clinical parameters examined were 5-year AMR/CMR (≥grade 2), coronary artery vasculopathy, and survival. RESULTS: At 2 years after transplant, freedom from AMR and/or CMR was 95.4% for those with no DSA (n=175), 66.9% for those with dnDSA (n=19), and 25% for those with DSA at transplant (n=6) (P<0.0001). Neither ≥17 nor ≥12 units of pretransplant levels indicated a significant difference in freedom from AMR and/or CMR. When both dnDSA and AT1R-ab ≥17 or ≥12 units were considered, freedom from AMR and/or CMR decreased to 50% and 45% (P<0.0001), respectively. Coronary artery vasculopathy and survival were not significantly impacted. CONCLUSIONS: These results show the increased negative impact of dnDSA and AT1R-ab on freedom from AMR and/or CMR and an increased hazard ratio when both parameters are considered. Both HLA- and non-HLA-specific antibodies seem to impact graft outcome in heart transplantation.