Interaction of B7‐H1 on intrahepatic cholangiocarcinoma cells with PD‐1 on tumor‐infiltrating T cells as a mechanism of immune evasion

Abstract

Background and Objectives The B7-H1/PD-1 pathway has recently been found to contribute to immune evasion of cancer cells from host immune system. This study aimed to investigate the expression of B7-H1 and its receptor PD-1 and to explore their significance in the progression of intraheptic cholangiocarcinoma (ICC). Methods Thirty-one surgically resected ICC tissues and the corresponding cancer adjacent tissues were enrolled from 2006 to 2007. Immunohistochemical studies were performed with antibody of B7-H1, PD-1, CD8, and CD4. Apoptosis status of tumor-infiltrating lymphocytes (TILs) was detected by TUNEL assay. Results Expression of B7-H1 and PD-1 was found to be up-regulated in ICC tissues compared with the cancer adjacent tissues. Tumor-related B7-H1 expression was significantly correlated with both tumor differentiation and pTNM stage and was inversely correlated with CD8+ TILs but not CD4+ TILs. TILs in primary carcinoma showed a high level of apoptosis. Conclusion B7-H1/PD-1 pathway may be linked to malignant potential of ICC and contribute to tumor immune evasion by promoting CD8+ TILs apoptosis. Thus, this pathway may indeed be a potential therapeutic target in the treatment of this disease. J. Surg. Oncol. 2009;100:500–504.