Moreover, a molecular analysis of Foxp3 and IL-10 was performed using a cultured human cholangiocarcinoma cell line. Consequently, 43% of the cholangiocarcinomas were found to be abundant in IgG4. Palbociclib supplier Those expressing HLA-DR but lacking costimulatory molecules (CD80 and CD86) and those expressing Foxp3 detected by an antibody recognizing the N terminus

accounted for 54% and 39% of cases, respectively. Moreover, the number of IgG4-positive cells was larger in these cases than in other groups. In cultured cells, the presence of a splicing variant of Foxp3 messenger RNA and the expression of IL-10 were demonstrated. Conclusion: Extrahepatic cholangiocarcinoma is often accompanied by significant infiltration of IgG4-positive cells. Cholangiocarcinoma cells could play the role of nonprofessional APCs and Foxp3-positive regulatory cells, inducing IgG4 reactions via the production of IL-10 indirectly and directly, respectively. (HEPATOLOGY CHIR99021 2012;56:157–164) Biliary tract cancers can be anatomically divided into intrahepatic and extrahepatic cholangiocarcinomas, the latter including hepatic hilar cancer, common bile duct cancer, gallbladder cancer, and cancer of the Papilla of Vater. The biological behavior and carcinogenesis of each cancer differ, but the histology of most biliary tract

cancers is the same as that of ordinary adenocarcinomas. In addition to neoplastic lesions, several types of

cholangitis causing biliary stenosis are important in the differential diagnosis of biliary diseases. Particularly, primary sclerosing cholangitis and a complication of immunoglobulin G4 (IgG4)-related systemic diseases, IgG4-related sclerosing cholangitis, clinicopathologically mimic extrahepatic cholangiocarcinomas. IgG4 is a minor immunoglobulin subtype composing 3%-6% of all the IgG circulating in adults,1 but is important for a systemic disorder, IgG4-related disease, that features elevated serum IgG4 levels and abundant infiltration with IgG4-positive plasma cells in affected organs.1-3 Moreover, IgG4-related cholangitis and pancreatitis (autoimmune pancreatitis, type 1) are characterized by sclerosing lesions (storiform fibrosis) and Morin Hydrate cholangiocarcinomas and pancreatic cancer usually accompany some degree of desmoplastic change and also, in some cases of pancreatic cancer, IgG4 reactions.4 Therefore, a pathological examination is necessary to differentiate IgG4-related diseases from tumors in pancreatico-biliary lesions. We have already observed that extrahepatic cholangiocarcinomas also accompany various degrees of IgG4 reactions assumed to be associated with the evasion of immunosurveillance (Kimura et al., unpublished data). However, the mechanisms inducing IgG4 reactions in cholangiocarcinoma tissue are still unknown.