Assessment of human leukocyte antigen matching algorithm PIRCHE‐II on liver transplantation outcomes

For liver transplantations, human leukocyte antigen (HLA) matching is not routinely performed because observed effects have been inconsistent. Nevertheless, long‐term liver transplantation outcomes remain suboptimal. The availability of a more precise HLA‐matching algorithm, Predicted Indirectly Recognizable HLA Epitopes II (PIRCHE‐II), now enables robust assessment of the association between HLA matching and liver transplantation outcomes. We performed a single‐center retrospective cohort study of 736 liver transplantation patients. Associations between PIRCHE‐II and HLAMatchmaker scores and mortality, graft loss, acute and chronic rejection, ischemic cholangiopathy, and disease recurrence were evaluated with Cox proportional hazards models. Associations between PIRCHE‐II with 1‐year, 2‐year, and 5‐year outcomes and severity of acute rejection were assessed with logistic and linear regression analyses, respectively. Subgroup analyses were performed for autoimmune and nonautoimmune indications, and patients aged 30 years and younger, and older than 30 years. PIRCHE‐II and HLAMatchmaker scores were not associated with any of the outcomes. However, patients who received transplants for autoimmune disease showed more acute rejection and graft loss, and these risks negatively associated with age. Rhesus mismatch more than doubled the risk of disease recurrence. Moreover, PIRCHE‐II was inversely associated with graft loss in the subgroup of patients aged 30 years and younger with autoimmune indications. The absence of associations between PIRCHE‐II and HLAMatchmaker scores and the studied outcomes refutes the need for HLA matching for liver (stem cell) transplantations for nonautoimmune disease. For autoimmune disease, the activated immune system seems to increase risks of acute rejection and graft loss. Our results may suggest the benefits of transplantations with rhesus matched but PIRCHE‐II mismatched donor livers.