In order to dissect the role of different subsets of antigen-presenting dendritic cell (DC) in autoimmune liver diseases, we analyzed the frequencies and phenotypes of DC1 and DC2 from patients with primary biliary cirrhosis (PBC) and autoimmune hepatitis (AIH). The numbers of DC, DC1 and DC2 in a fixed amount of peripheral blood (20 ml) from 14 patients with PBC (therapy [-]: 5, therapy [+]: 9), seven patients with AIH (therapy [-]): 4, therapy [+]: 3), nine patients with chronic hepatitis due to hepatitis C virus and 12 healthy subjects were estimated using three-color flow cytometry. The mean fluorescence intensities of HLA DR, CD11c and CD123 on DC subsets were evaluated from the flow cytometric profiles. The numbers of DC1 and DC2 did not differ significantly among patients and controls. The expression of HLA DR was lower on DC1 from patients with AIH, but not on PBC. However, the levels of HLA DR and CD 123 on DC2 were significantly decreased in patients with PBC (therapy [-]) and AIH (therapy [-]) compared with healthy subjects (P<0.05). Defective phenotype of DC2 in both AIH and PBC may have a relevance to the breakdown of tolerance to self antigen in these autoimmune diseases. Functional study of DC2 in autoimmune liver diseases is warranted.