Abstract 18156: Donor Specific Alloantibodies to HLA II Antigens Result in Accelerated Cardiac Allograft Vasculopathy Assessed by 3d Volumetric Ivus

Abstract

BACKGROUND: The immunologic risk associated with preformed donor-specific allo-antibodies (DSA) against human leukocyte antigens (HLA) in heart transplant (HTX) recipients is unclear. The goal of this study was to evaluate potential role of DSA on the progression of cardiac allograft vasculopathy (CAV) in HTX recipients. METHODS: The presence of DSA against HLA was evaluated using solid phase Single Antigen Bead assay (One Lambda, Inc., Canoga Park, CA; Luminex platform) before transplant in 35 HTX recipients. Using alloantibody specification analysis, 11% (4/35) and 20% (7/35) had DSA against donor Class I and II HLA respectively including the one patient who had both (DSA I & II+) . 71% (25/35) of patients had no demonstrable DSA (DSA-). All patients had negative cytotoxicity cross match. Baseline three-dimensional intravascular ultrasound studies (3D IVUS) were performed at 1.0 [0.18, 1.4] year after transplant. Follow up 3D IVUS exams were performed 0.92 [0.85, 1.04] years after the baseline exam. RESULTS: The increase in mean plaque (media and intima) volume (PV) was accelerated in the DSA II+ group as compared to the DSA- group (0.87±1.9 mm (3)/mm vs. 0.16±1.8 mm (3)/mm) but the vessel volume index (follow up vessel volume/ baseline vessel volume) was similar between groups (1.08±0.5 vs. 1.09± 0.4; p=0.9). Plaque index (PI) (PV/vessel volume x 100 [%]) increased significantly in the DSA II+ group (17.9±6.3%) but not in the DSA- group (-13.6±13.2%, P=0.02). None of these values were significant in the DSA I+ only group. Treatment with Sirolimus did not affect PI progression between the DSA II+ and DSA- groups (PI progression: 15.9±8.7% vs. -11.7±7.1%, P=0.03). Age, gender, lipid and uric acid levels, prevalence of diabetes, ischemic time, time between IVUS examinations, the use of steroids, mycophenolate vs. azathioprine or calcineurin inhibitors vs. sirolimus were not different between the groups (P>0.4 for all). CONCLUSIONS: Heart transplant recipients with clearly defined anti-Class II DSA are at risk for accelerated cardiac allograft vasculopathy. Whether interventions to minimize the risk of DSA such as virtual crossmatch, desensitization and complement inhibition will retard CAV remains to be proven.