Abstract: Objective To investigate the expressions of programmed death 1 (PD-1) and programmed death ligand 1 (PD-L1) in hepatic tissues of patients with autoimmune hepatitis (AIH), and to explore their roles in the pathogenesis of AIH. Methods The expressions of PD-1 and PD-L1 in hepatic tissues from 43 AIH patients and 9 healthy controls were detected by immunohistochemistry combined with computer image quantitative analysis. Results The PD-1 and PD-L1 expressions in hepatic tissues of AIH patients were 10.12±5.31% and 7.45±4.29%, respectively, which were significantly higher than those in controls (1.74±0.37% and 1.48±0.32%, respectively). The expressions of PD-1 and PD-L1 in hepatic tissues of AIH patients at active stage were 15.68±6.31% and 7.45±4.29%, respectively, which were higher than those in AIH patients in remission (6.24±3.25% and 4.78±2.43%, respectively) and healthy controls (1.74±0.37% and 1.48±0.32%, respectively). Conclusion PD-1 and PD-L1 are overexpressed in hepatic tissues of AIH patients, which reveals that PD-1 and its ligand might play an important role in the pathogenesis of AIH.

Key words: AIH, PD-1, PD-L1, Liver tissues, Immunohistochemistry