Prognostic impact of CD8+ T cell distribution and its association with the HLA class I expression in intrahepatic cholangiocarcinoma

PURPOSE: A lack of effective systemic therapy is one reason for the poor prognosis of intrahepatic cholangiocarcinoma. Newly developed immune checkpoint inhibitors function by minimizing CD8+ T cell suppression to improve tumor-specific responses. This study aimed to examine the characteristics of CD8+ T cells in intrahepatic cholangiocarcinoma. METHODS: Clinicopathological data, including the overall survival, of 69 cases of postoperative intrahepatic cholangiocarcinoma were prospectively investigated. We then immunohistochemically stained for CD8, Foxp3, CD163, PD-L1, and human leukocyte antigen (HLA) class I and counted the number of CD8+ T cells, Foxp3+ T cells, and CD163+ macrophages in different areas (outer border, interborder, and intratumor). RESULTS: A significant difference was found in the 5-year overall survival between the CD8+ T cell high group (45.5%) and low group (24.7%) in the outer border area (p = 0.0103). Furthermore, the number of CD8+ T cells and the high expression of HLA class I were positively correlated (p = 0.0341). CONCLUSION: The number of CD8+ T cells in the outer border area of the tumor correlated with the HLA class I expression of intrahepatic cholangiocarcinoma and may therefore be a prognostic factor for patients with postoperative intrahepatic cholangiocarcinoma.