CD4 and hilar cholangiocarcinoma: Figure 1 illustrates the representative images of immunohistochemical features of high-level and low-level tumor-infiltrating inflammatory cells in hilar cholangiocarcinoma. All patients were divided into the high group of CD3+, CD4+ and CD8+ TILs and the low group of CD3+, CD4+ and CD8+ TILs based on the median number of TILs, respectively.