Expression of Fas and Fas ligand reflects the biological characteristics but not the status of apoptosis of intrahepatic cholangiocellular carcinoma

Although intrahepatic cholangiocellular carcinoma (CCC) is the second most common of hepatic malignancies, there have been few studies evaluating its biological characteristics. We therefore decided to investigate the status of apoptosis and of Pas and Fas ligand expression in this carcinoma. We per formed immunohistochemistry for Fas and Fas ligand in 40 CCC cases and eval uated the apoptotic index (AI) by counting the number of morphologically ap optotic cells per 1000 cells. AI was higher in cases with poor differentiat ion, lymph node metastasis and high Ki-67 labeling index (LI). Fas expressi on in CCC cells decreased in cases with poor differentiation and high Ki-67 LI. Fas ligand expression in the stromal infiltrating mononuclear cells di d not correlate with any clinicopathological features of CCC, but was direc tly related to Fas expression in CCC cells. Fas ligand was also expressed i n CCC cells in 27.5% of the cases and more frequently observed in cases wit h moderate or poor differentiation and high Ki-67 LI. None of these three p arameters correlated with AI. These findings indicate that, in CCC, i) case s showing rapid growth characteristics are less likely to die of Pas-mediat ed apoptosis and more likely to display counterattack to lymphocytes via Fa s ligand expressed by carcinoma cells; ii) stromal mononuclear cells expres s Fas ligand in response to Fas expression in carcinoma cells; iii) Pas and Fas ligand expression are not related to the status of apoptosis.