Table 1.
Immunosuppressive cells | Substance that causes its aggregation or production | Function and mechanism |
---|---|---|
MDSCs | VEGF, IL-6, GM-CSF | induction of T cell tolerance; inhibition of activated T cells; downregulation of anti-tumor immunity through innate immune regulation |
Treg cells | CCR4-CCL17/22, CCR8-CCL1, CCR10-CCL28, and CXCR3-CCL10 | destruction of APCs by expressing IL-2, TGF-β, and IL-10; inhibition of effector T cells through the MHC class II by ligand LAG-3; inhibition of T cells by regulating IDO in DCs; inhibition of DCs through CTLA-4, impairs APC maturation |
TAMs | (1) CXCL9, CXCL10, TNF-α, IL-1, IL-6, and IL-12 can induce the M1 phenotype; (2) IL-4, IL-10, and IL-13 can induce the M2 phenotype | M1 macrophages kill microorganisms and tumor cells by ROS; M2 macrophages initiate anti-tumor immunity through Th2; M2 macrophages lose the ability to present antigen; activated M2 macrophages downregulate M1 by secreting anti-inflammatory cytokines; M2 macrophages downregulate anti-tumor immunity by expressing IL-1β, IL-10, MMPs, and TGF-β |
CAFs | fibroblasts are transformed into CAFs through TGF-β and IL-1β signaling pathways | inhibition of T cell proliferation through VEGF and TGF-β; induction of immune suppression by inducing Treg cells; combine with tumor cells to establish an immunosuppressive network; help tumor cells escape the body’s immune killing effect by gathering M2 macrophages and MDSCs; regulation of the microenvironment by activating ECM remodeling and degradation |
GM-CSF, granulocyte-macrophage colony-stimulating factor.