Abstract: Objective The aim of this study was to analyze the changes of peripheral blood mononuclear cell (PBMC) Toll-like receptor 2 (TLR2) and cytotoxic T lymphocyte associated antigen-4 (CTLA-4) in patients with autoimmune hepatitis (AIH). Methods 47 patients with AIH and 50 healthy subjects were encountered in our hospital between June 2018 and June 2022, and all patients with AIH received liver biopsies. The peripheral blood was drawn for separation of PBMCs, the TLR2 and CTLA-4 mRNA in PBMCs were detected by PCR, and the percentages of TLR2 and CTLA-4 positive PBMCs were detected by flow cytometry. Results The PBMC TLR2 mRNA level and the percentage of TLR2 positive PBMCs in patients with AIH were (1.7±0.4) and (34.2±7.9)%, both significantly higher than [(0.9±0.2) and (21.4±3.5)%, respectively, P<0.05], while the PBMCs CTLA-4 mRNA level and the percentage of CTLA-4 positive PBMCs were (0.5±0.2) and (2.3±0.8)%, both significantly lower than [(1.1±0.2) and (13.7±3.9)%, respectively, P<0.05] in healthy persons; the PBMC TLR2 mRNA level and the percentage of TLR2 positive PBMCs in 21 AIH patients with grade G3/G4 were(1.9±0.3) and (37.2±5.7)%, both much higher than [(1.5±0.3) and (30.5±6.2)%, respectively, P<0.05] in 26 AIH patients with grade G1/G2, while the PBMCs CTLA-4 mRNA level and the percentage of CTLA-4 positive PBMCs were (0.3±0.1) and (1.9±0.6)%, both much lower than [(0.7±0.2) and (2.6±0.8)%, respectively, P<0.05] in patients with G1/G2; the PBMC TLR2 mRNA level and the percentage of TLR2 positive PBMCs in 17 AIH patients with stage F3/F4 were(1.9±0.3) and (37.6±5.3)%, both much higher than [(1.6±0.3) and (32.9±4.2)%, respectively, P<0.05] in 25 patients with stage F1/F2 or [(1.3±0.2) and (28.7±1.9)%, respectively, P<0.05] in 5 patients without liver fibrosis, while the PBMCs CTLA-4 mRNA level and the percentage of CTLA-4 positive PBMCs were(0.3±0.1) and (1.8±0.6)%, both much lower than [(0.6±0.2) and (2.3±0.7)%, respectively, P<0.05] in patients with stage F1/F2 or [(0.9±0.2) and (4.2±0.4)%, respectively, P<0.05] in patients with stage F0. Conclusion The PBMC TLR2 mRNA levels and the percentage of TLR2 positive PBMCs increase, and the PBMCs CTLA-4 mRNA level and the percentage of CTLA-4 positive PBMCs decrease in patients with AIH, which might be correlated to the hepatic activity index and liver fibrosis staging, and needs further investigation.

Key words: Autoimmune hepatitis, Peripheral blood mononuclear cells, Toll-like receptor 2, Cytotoxic T lymphocyte associated antigen 4, Liver pathology