*Purpose: Recent reports indicated important while inconsistent roles of preformed donor specific antibody (DSA) to HLA in liver transplantation. Re-transplant liver patients were understudied due to worse outcome than 1^st graft. Auto antibodies to Angiotensin II Type I Receptor (AT1R) have been reported to be detrimental for survival of kidney transplant but weren’t studied in liver transplantation. In this study, we try to determine the roles of preformed DSA and anti-AT1R auto antibodies in long-term survival of 2^nd liver transplant.

*Methods: We retrospectively reviewed patients (1991-2018) undergoing a 2^nd liver transplantation in our centre with available pre-operative serum and donor HLA typing. Patients who received ABO incompatible, multiple organ transplants or incomplete demographics were excluded. Banked sera were tested for anti-HLA antibodies with Luminex-based solid phase assays. Anti-AT1R antibodies were tested with ELISA kit. All statistical analyses were done with IBM SPSS version 25.

*Results: We included 94 patients in this study. With long follow-up up to 25 years, 48 (51.1%) patients had lost 2^nd liver transplant. Preformed DSA to 2nd liver transplant were found in 34 (36.2%) patients. Surprisingly, 48 (51.1%) patients had positive anti-AT1R antibody >17U/ml; 22 (23.4%) had anti-AT1R antibody>40U/ml so extra dilutions were performed for accurate measurement. When backward stepwise methods were used to select covariates in multivariate cox regression, only three variables were left in model: MELD (Model for End-Stage Liver Disease) Score [HR=1.061 (1.019-1.105), p=0.004] and AT1R antibody>40U/ml [HR=2.241 (1.125-4.467), p=0.02] were significant risk factors for survival of the 2nd liver transplant; there was non-significant trend toward worse graft survival in male patients [HR=1.92(0.917-4.024), p=0.08]. Class, loci, strength of DSA, other patient/donor characteristics such as age, primary diseases, causes of loss 1^st graft, survival of 1^st graft, cold ischemia time were found to be insignificant for liver graft survival. MELD score [AUC=0.700(0.577-0.823), p=0.004] and AT1R antibody [AUC=0.64(0.528-0.753), p=0.02] quantitatively predicted graft loss in receiver operating characteristic analysis. Patients with AT1R antibody>40U/ml had significant worse survival of 2^nd liver graft (p=0.035) in Kaplan-Meier analysis (Figure below).

*Conclusions: High MELD score and anti-AT1R antibody, not preformed DSA, were found to be associated with inferior outcomes of 2^nd liver transplant.

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