Notably, we detected a decrease in the frequency of circulating Th1/17 cells (CD4+ T lymphocytes with the plasticity to produce both IFN-γ and IL-17 cytokines), together with a decrease in the frequency of circulating Tc17 cells in CCA and HCC patients, pointing to an active migration of Th1/17 and Tc17 cells from the peripheral blood to the tumor microenvironment. This evidence concerns the gene CD4 and cholangiocarcinoma.