Fas-Fas ligand pathway does not actively work in extrahepatic bile duct carcinoma.

Fas and Fas ligand expression were immunohistochemically investigated in 34 extrahepatic bile duct carcinomas (BDC) and nine ampulla carcinomas (AC). Fas expression was regarded as positive in 22 BDC cases (64.7%). The absence or decreased expression of Fas was frequently observed in cases with high biological aggressiveness such as advanced stage, moderate or poor differentiation, lymph node metastasis, aberrant p53 expression and high Ki-67 labeling index. A similar tendency was observed in AC where two cases without Fas expression were poorly differentiated with a high Ki-67 labeling index. Fas ligand expression in infiltrating mononuclear cells adjacent to the carcinoma nests was observed in only four BDC (11.1%) and in none of the AC examined. Fas ligand expression in carcinoma cells was observed in only one BDC, which showed Fas ligand expression also in mononuclear cells and not in any AC case. These results suggest that, although BDC and AC very frequently express Fas, Fas-mediated apoptosis is only occasionally induced in carcinoma cells because of the lack of Fas ligand expression in infiltrating mononuclear cells in these carcinomas.