Abstract: Objective To investigate the expressions of programmed death-1 （PD-1） and programmed death ligand-1 （PD-L1） in peripheral blood T lymphocytes of patients with autoimmune hepatitis and their correlation with liver function indexes. Methods 131 patients with autoimmune hepatitis admitted in our hospital from January 2016 to July 2021 were selected as the disease group,and the 112 healthy people were selected as the control group at the same period according to the matching principle,another 93 cases of hepatic hemangioma patients with matched clinical data were taken as the hepatic hemangioma group. The expression levels of PD-1 and PD-L1 in peripheral blood CD4⁺ and CD8⁺ T lymphocytes were detected and compared. The expressions of PD-1 and PD-L1 in T lymphocytes of patients with different stages of disease in the disease group were compared,and the liver function related indexes [Total bilirubin （TBIL）,direct bilirubin（DBIL）,indirect bilirubin （IBIL）,alanine aminotransferase（ALT）,aspartate aminotransferase（AST）,total protein（TP）, albumin（ALB）,gamma glutamyltranspeptidase（GGT）,alkaline phosphatase（ALP）] among the disease group, hepatic hemangioma group and the control group were compared. In addition, the relationships between the expressions of PD-1 and PD-L1 in peripheral blood T lymphocytes and the liver function related indexes in patients with autoimmune hepatitis were analyzed by the Pearson correlation analysis method, and the expressions of PD-1 and PD-L1 in peripheral blood T lymphocytes of patients with different Child-Pugh grades of liver function were compared. Results The expression rates of PD-1 and PD-L1 in peripheral blood CD4⁺ and CD8⁺ T lymphocytes in the disease group were significantly higher than those in the hepatic hemangioma group and control group（P<0.05）,but there was no significant difference between the hepatic hemangioma group and the control group（P>0.05）. The expression rates of PD-1 and PD-L1 in peripheral blood CD4⁺ and CD8⁺ T lymphocytes increased gradually in patients with mild,moderate and severe autoimmune hepatitis,and the differences were statistically significant（P<0.05）. The levels of serum TBIL,DBIL,IBIL,ALT,AST, GGT and ALP in the disease group were significantly higher than those in the hepatic hemangioma group and control group （P<0.05）,but the levels of TP and ALB in the disease group were lower than those in the hepatic hemangioma group and control group（P<0.05）. There was no significant difference in the levels of liver function related indexes between the hepatic hemangioma group and the control group（P>0.05）. Pearson correlation analysis showed that the expression rates of PD-1 and PD-L1 in peripheral blood CD4⁺ and CD8⁺ T lymphocytes of the disease group patients were significantly positively correlated with the levels of TBIL,DBIL,IBIL,ALT,AST,GGT and ALP（P<0.05）,but they were negatively correlated with the levels of TP and ALB（P<0.05）. The expression rates of PD-1 and PD-L1in peripheral blood CD4⁺ and CD8⁺ T lymphocytes increased successively in Child-Pugh grade A,B and C of liver function in patients with autoimmune hepatitis,and the differences were statistically significant（P<0.05）. Conclusion The PD-1 and PD-L1 are highly expressed in peripheral blood T lymphocytes of patients with autoimmune hepatitis,and they are closely related to the severity of the disease and liver function, which are important for clinical diagnosis and treatment.

Key words: Autoimmune hepatitis, T lymphocyte, Programmed death-1, Programmed death ligand-1, Liver function, Correlation