Type1 and type2 memory T cells imbalance shown by expression of intrahepatic chemokine receptors relates to pathogenesis of primary biliary cirrhosis.

Primary biliary cirrhosis (PBC) is characterized by the immunopathologic destruction of interlobular bile ducts. Generally, immunereaction induced by the antigenetic stimulation is divided to cellular and humoral reactions, which are regulated by type1 and type2 memory T cells, respectively. The relative strength of type1 and type2 responses is an important factor in the pathophysiology of immune-mediated diseases. Chemokine receptors are disproportionally expressed in type1 and type2 T cells, providing a basis for tissue-specific recruitment of helper and cytotoxic T cell subsets. In this study, the expression of CXC chemokine receptor 3 (CXCR3) and CC chemokine receptor 4 (CCR4), which are preferentially expressed on type1 and type2, respectively, were examined to clarify their imbalance in the PBC liver tissue (23 cases). As a control, 16 livers of chronic viral hepatitis (CVH) were used. Reverse transcription-polymerase chain reaction and semiquantitative analysis revealed that the relative ratio of CXCR3/CCR4 mRNAs was higher in early PBC (0.76+/-0.56) rather than in advanced PBC (0.25+/-0.11), and was comparable to that in active CVH (0.67+/-0.43). By immunohistochemistry, the ratio of CXCR3-/CCR4-positive mononuclear cells in portal tracts of early PBC (4.77+/-1.70) is significantly higher than that of advanced PBC (3.11+/-1.26), and also than that of mild and of active CVH. In early PBC, mononuclear cells positive for CXCR3 were dense around the damaged bile ducts. These data suggest that the enhanced shift toward type1 occurs in portal tracts of early PBC and that the imbalance of type1/type2 changes during the course of PBC. This study provides further support for the state of enhanced type1 response in early PBC and potentially offers a possibility to suppress the bile duct lesions and to prevent the progression of PBC from early to advanced stages by reversing the type1/type2 imbalance.