Abstract: Objective The aim of this study was to investigate the implication of peripheral blood mononuclear CD6 positive cell percentage and its ligand activated leukocyte adhesion molecule (ALCAM) levels in patients with autoimmune hepatitis (AIH). Methods 60 patients with AIH were enrolled in this study between March 2020 and March 2022, and all received liver biopsies. The peripheral blood mononuclear cells (PBMCs) were separated and the percentages of CD 6 positive cells were detected by FCM. Serum ALCAM levels were assayed by ELISA. Results Our series of patients with AIH included clinically mild/moderate disease in 42 cases and severe in 18 cases, and the histopathologically showed <= grade 1 of liver inflammatory activity in 48 cases and ≥grade 2 in 12 cases, and <= stage 1 of liver fibrosis in 44 cases and ≥stage 2 in 16 cases; total serum bilirubin, ALT, AST and ALP levels in patients with severe disease were(94.5±8.3)μmol/L, (215.4±17.2)U/L, (161.5±14.2)U/L and (83.6±16.3)U/L, all significantly higher than [(31.1±4.3)μmol/L, (58.2±9.4)U/L, (49.5±8.3)U/L and (61.6±3.5)U/L, P<0.05] in patients with mild/moderate diseases; the percentage of PBMC CD6 positive cells and serum ALCAM, IgG and IgM levels in patients with severe disease were(65.4±7.8)%, (22.5±2.1)ng/mL, (18.6±2.6)mg/dL and (1.7±0.3)mg/dL, all much higher than [(36.7±4.2)%, (15.4±1.2)ng/mL, (13.7±2.3)mg/dL and (0.7±0.1)mg/dL, respectively, P<0.05] in patients with mild/moderate disease; the percentage of CD6 positive cells and serum ALCAM levels in patients with ≥grade 2 were (71.4±8.3)% and (25.4±3.2)ng/mL, both significantly higher than [(36.2±4.3)% and (14.8±1.4)ng/mL, P<0.05] in patients with <=grade 1, and they were(69.3±7.8)% and (24.7±3.4)ng/mL in patients with ≥stage 2, both much higher than [(36.4±4.4)% and (14.9±1.8)ng/mL, P<0.05] in those with <=stage 1; the AUCs were 0.98 and 0.95, with the sensitivities (Se) of 100.0% and 91.6% and the specificities (Sp) of 87.5% and 97.9%, when the PBMC CD6 positive cells and serum ALCAM levels were applied to predict the significant histoactivities, and the AUCs were 0.98 and 0.90, with the Se of 93.7% and 75.0%, and Sp of 95.5% and 100.00%, when the two were applied to predict significant liver fibrosis. Conclusion The percentages of PBMC CD6 positive cells and serum ALCAM levels in patients with AIH increase, which might be correlated to intrahepatic liver inflammation and fibrosis.

Key words: Autoimmune hepatitis, CD6, Activated leukocyte adhesion molecule, Liver histopathology