Aberrant cytokeratin expression and high susceptibility to apoptosis in autoimmune hepatitis.

Immunopathological differences between autoimmune hepatitis (AIH) and chronic hepatitis C (CH-C) have not been well investigated. Therefore, we immunohistochemically examined the expression of various cytokeratins (CKs) not only in liver tissues of AIH but also in those of CH-C at the active stage. Furthermore, to evaluate the immune surveillance system and the susceptibility to apoptosis, immunohistochemical staining of human leukocyte antigen (HLA)-DRalpha, cathepsin D, B cell leukemia-2 (bcl-2), bcl-2-associated X protein (bax) and caspase 3 was also performed. Heterogeneous expression of CK 8 and CK 18 was observed in hepatocytes of AIH, while homogeneous expression was observed in hepatocytes of CH-C. Aberrant expression of CK 7 and CK 19 was observed in hepatocytes of AIH, while it was not in hepatocytes of CH-C. Expression of HLA-DRalpha was observed in hepatocytes of AIH but not in those of CH-C. Furthermore, expression of cathepsin D, bax and caspase 3 was much stronger in hepatocytes of AIH than in those of CH-C. These results indicate that cytoskeletal alterations of hepatocytes in AIH may increase the susceptibility to apoptosis and induce hepatocyte destruction.