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Fig. 3 | Journal of Experimental & Clinical Cancer Research

Fig. 3

From: The role of tumor-infiltrating lymphocytes in cholangiocarcinoma

Fig. 3

Overview of different types of tumor-infiltrating lymphocytes in CCA. TILs are a highly heterogeneous group of lymphocytes. Distinct cell subsets play different roles in the tumor microenvironment. CD4+ cells are activated by reaction with peptide antigens delivered by major histocompatibility complex II (MHC II) and secrete cytokines such as IFN-γ, TNF-α and IL-2, which mediate cellular immunity and enhance the killing ability of NK cells and cytotoxic T cells. CD8+ cytotoxic T cells destroy tumor cells directly by releasing chemicals like perforin and granzyme and indirectly by inducing apoptosis by expressing FasL or secreting TNF-α attaching to target cell surface receptors. NK cells kill tumor cells by the same mechanisms as CD8+ cytotoxic T cells. Tregs suppress CD8+ cytotoxic T cells and NK cells by secreting soluble anti-inflammatory chemicals such as IL-10 and TGF-β. CD, cluster of differenciation; FasL, Fas ligand; IFN; interferon; IL, interleukin; MHC; major histocompatibility complex; NK, natural killer; TGF, transforming growth factor; TILs, tumor-infiltrating lymphocytes; TNF, tumor necrosis factor; Tregs; regulatory T cells

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