Abstract: Objective The aim of this study was to investigate peripheral blood lymphocyte spectrum and immune checkpoint receptors and their ligand expression in patients with drug-induced liver injury (DILI). Methods 62 patients with DILI, 35 patients with autoimmune hepatitis (AIH) and 40 patients with nonalcoholic fatty liver disease (NAFLD) were recruited in our hospital between March 2020 and March 2023, and peripheral blood lymphocyte spectrum and immune checkpoints receptors and their ligand expression were detected by FCM. Results The percentage of peripheral blood activated Th cells in patients with DILI was (14.2±3.8)%, significantly higher than [(9.7±2.3)%, P<0.05] in patients with AIH or [(8.2±2.7)%, P<0.05] in patients with NAFLD, the percentage of peripheral blood activated TC cells in patients with DILI and AIH were (31.3±9.2)% and (32.2±7.7)%, significantly higher than [(22.6±5.9)%, P<0.05] in patients with NAFLD, while the percentages of Th9 cells were (19.7±3.3)% and (19.2±2.8)%, much lower than [(25.3±5.4)%, P<0.05] in patients with NAFLD, and the percentages of Th1 cells in patients with DILI and NAFLD were (52.6±12.3)% and (53.2±11.8), much higher than [(43.4±10.7)%, P<0.05] in patients with AIH; the percentage of Th cells with ICOS expression positive in patients with DILI was (5.2±1.5)%, much higher than [(3.9±1.1)%, P<0.05] in patients with AIH or [(1.9±0.8), P<0.05] in patients with NAFLD, while the percentages of Th cells with CTLA-4 and PD-1 expression positive in patients with AIH were (37.4±5.1)% and (15.7±2.3)%, much higher than [(28.3±3.4)% and (12.8±1.9)%, respectively, P<0.05] in patients with DILI or [(18.2±3.2)% and (10.2±1.6)%, respectively, P<0.05] in those with NAFLD. Conclusion During the progress of DILI, the number of peripheral blood activated T lymphocytes increases, which might participate in the pathogenesis of this entity, and needs further investigation.

Key words: Drug induced liver injury, Lymphocyte spectrum, Immune checkpoint