Abstract: Objective To investigate the expression of programmed death receptor 1 （PD-1） in liver tissue of patients with autoimmune hepatitis（AIH） and its clinical implications. Methods 68 patients with AIH （48 active and 20 at remission） were admitted to our hospital between May 2015 and April 2017,and liver biopsies were performed. 13 patients with hepatic hemangioma were included and their liver tissues were obtained by surgery for control. The expression of PD-1 in liver tissues was detected by immunochemical staining. The correlation between the positive expression of PD-1 in liver tissues and serum liver function indexes in patients with AIH was analyzed. Results Serum bilirubin,AST, ALT,ALP and GGT levels in 48 patients with active AIH were （72.1±48.9） μmol/L,（243.1±170.4） U/L,（345.3±217.7） U/L,（154.3±94.6） U/L and （86.5±43.5） U/L,much higher than（14.8±4.2） μmol/L,（28.3±8.7） U/L,（27.6±8.8） U/L,（73.3±51.3） U/L and （71.3±27.3） U/L in 20 patients at remission （all P<0.05）,and serum globulin and IgG levels were （34.3±11.3） g/L and （23.2±7.5） g/L,much higher than （30.7±10.2） g/L and （11.7±4.6）g/L in patients at remission（P<0.05）;the positive rate of PD-1 expression in liver tissues of 68 patients with AIH was（13.61±6.87）%,significantly higher than （2.25±0.68）% in patients with hepatic hemangioma（P<0.05）,and the positive rate in 48 patients with active AIH was（16.56±7.81） %,significantly higher than（6.56±3.21）% in patients at remission（P<0.05）;the incidences of interfacial inflammation,lymphocyte invasion and single tube destructive inflammation in 48 patients with active AIH were 93.75%,89.58% and 6.25%;the PD-1 expressions in liver tissues of patients with active AIH were positively correlated to serum bilirubin（r=0.996,P<0.001）,AST（r=0.989,P<0.001）,ALT（r=0.995,P<0.001）,ALP（r=0.998,P<0.001）,GGT（r=0.995,P<0.001）,GLO（r=0.996,P<0.001） and IgG levels（r=0.997,P<0.001）,and they were positively correlated to serum bilirubin （r=0.999,P<0.001）,AST（r=0.999,P<0.001）,ALT （r=0.999,P<0.001）,ALP（r=0.999,P<0.001）,GGT（r=0.999,P<0.001） and IgG levels（r=0.999,P<0.001） in patients at remission. Conclusion The expression of PD-1 in liver tissues of patients with AIH is strongly intensified and positively correlated to hepatic activity index,and the mechanism by which it take part in the pathogenesis of AIH needs further investigation.

Key words: Autoimmune hepatitis, Programmed death receptor-1, Hepatic activity index, Pathology