Aim: to examine the impact of preformed IgG3 donor-specific HLA antibodies (DSA) in early acute rejection after liver transplantation (LT).

Methods: We analyzed 1271 adult LT recipients from 2000 to 2009 with serum available for DSA determination (96% of patients transplanted). All sera were analyzed for DSA using LABScreen single antigen beads and MFI >5000 was considered positive. All DSA positive sera were analyzed for the presence of IgG3 subclass DSA and MFI >500 was considered positive.

Results: 65% of patients were male, 73% were Caucasian, with a median age of 52. The most common indications for LT were HCV in 31%, HCC in 24%, and autoimmune conditions in 14%. 44% of patients received induction therapy. Immunosuppression at 3 months included tacrolimus 65%, MMF 51%, sirolimus 15%, and steroids 54% of the time. Preformed DSA was observed in 14% of patients, and 32% of these were of the IgG3 subclass. Patients with preformed DSA had significantly higher rates of early acute rejection when compared to patients without preformed DSA (44% vs. 36%, p=0.004, figure 1). Patients with preformed DSA of the IgG3 subclass had a higher risk of early acute rejection compared to IgG3 negative patients (49% vs. 37%, p=0.05, figure 2).

Conclusion: Patients with preformed DSA show acute rejection rates 8% higher than in patients without preformed DSA. This difference is increased to 12% if the DSA is of the IgG3 subclass. IgG3 DSA may be a helpful additional biomarker to predict risk for acute rejection after liver transplantation.

BaÑuelos, N.: Employee, One Lambda, Inc. Terasaki, P.: Stockholder, One Lambda, Inc.

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