Abstract: Objective To study the differences of serum IgG4 levels in various autoimmune liver diseases and to analyze the clinical characterization of patients with high serum IgG4 levels. Methods 65 patients with autoimmune liver diseases were enrolled for this study including 11 patients with autoimmune hepatitis （AIH）,47 patients with primary biliary cirrhosis（PBC） and 7 patients with overlap syndrome of AIH and PBC. The serum IgG4 levels was detected by immuno-scatter turbidmetry. The differences of serum IgG4 levels in the three groups were studied. The clinical features of patients with autoimmune liver disease were analyzed according to their serum IgG4 levels. The significance of inter-group differences of measurement data was assessed by Student’s t-test or Mann-Whitney U test and enumeration data by Fisher’s exact test. Results The serum IgG4 levels in patients with AIH was 642.2 mg/L（97.7 mg/L~1687.0 mg/L）,a little higher than in patients with PBC [153.9 mg/L（78.9 mg/L~400.3 mg/L）,P=0.076] and in with overlap syndrome [229.9 mg/L（154.9 mg/L ~417.9 mg/L）,P=0.388];Three patients with AIH had high serum IgG4 levels （≥1350 mg/L） out of 11 patients with AIH. The ratio of IgG4/IgG was higher in the three patients with higher as compared to 8 with relatively low serum IgG4 levels（P<0.05）;The three patients with elevated IgG4 levels had diabetes mellitus type 2 and one of them was also complicated with rheumatoid arthritis, whereas the other 8 patients with low serum IgG4 levels were not;14 patients with PBC with higher serum IgG4 levels（≥200 mg/L） had higher total serum bilirubin levels as compared to those in 33 patients with relatively low serum IgG4 levels [（45.09±74.85）μmol/L vs.（26.38±23.03） μmol/L,P=0.05）]. Conclusion Compared with patients with PBC or overlap syndrome of AIH and PBC,the patients with AIH have a higher serum IgG4 levels. The patients with AIH with high serum IgG4 levels might be complicated with other autoimmune or metabolic diseases.

Key words: Autoimmune liver disease, Immunoglobulin G4, Clinical feature