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. 2023 Oct 27;63(6):137. doi: 10.3892/ijo.2023.5585

Figure 3.

Figure 3

Roles of Tregs in the establishment of the immunosuppressive tumor immune microenvironment. Tregs originate from tumor-infiltrating T-cells under the stimulation of CCL2 produced by tumor cells, TAMs and CAFs. They play a suppressive role mainly through the following mechanisms: i) Tregs suppress T-cell and NK cell immune activity by releasing abundant TGF-β and IL-10; ii) they bind to IL-2 to inhibit the activation of other immune cells; iii) CTLA-4 expressed by Tregs binds to CD80 on antigen-presenting cells to attenuate the cytotoxic effects of CD8+ T-cells; iv) they induce macrophage differentiation toward the tumor-promoting M2 subtype. Tregs, regulatory T-cells; CCL2, chemokine ligand 2; TAMs, tumor-associated macrophages; CAF, cancer-associated fibroblasts; NK, natural killer; CTLA-4, cytotoxic T-lymphocyte-associated antigen-4; APC, antigen-presenting cell; TIME, tumor immune microenvironment.