Helper T lymphocytes specific for cytokeratin 19 in patients with primary biliary cirrhosis

We demonstrated the expression of cytokeratin 19 (CK19) in biliary cells in chronic non-suppurative destructive cholangitis (CNSDC) and hypothesized that this expression may have a correlation with the disease process in addition to cellular immunity which is believed to be involved in the pathogenesis of primary biliary cirrhosis (PBC). It is, therefore, important to clarify whether the destruction of bile ducts and biliary cells are caused by cellular immunity including helper T lymphocytes (Ths) and cytotoxic T lymphocytes (CTLs) specific for CK19. We examined the existence of helper T lymphocytes specific for CK19 in patients with PBC. As a result, the frequencies of responders having CK19 specific helper T lymphocytes and the stimulation index (SI) of the proliferative responses of peripheral blood mononuclear cells (PBMCs) were significantly higher and larger in patients with PBC compared with those of patients with chronic hepatitis C and normal subjects. The phenotype of proliferating PBMCs specific for CK19 were predominantly CD4+ Th1 cells. The Th1 response may help the induction of CTLs specific for CK19, and these CTLs could attack biliary cells.