Figure 4.

Th17 cells and PTC. Th17 cells exert indirect antitumor effects by secreting chemokines such as CXCL-9 and CXCL-10 to attract effector cells such as Th1 and CD8⁺ T cells and NK cells to accumulate and kill tumor cells in tumor tissues. Th17 cells can also inhibit the formation of tumor blood vessels and promote PTC cell apoptosis by producing IFN-γ, TNF-α and IL-17. IL-17 can enhance the effect of IL-6, transforming CD4⁺ T cells into Th17 cells. PTC cells can produce CCL2, which stimulates monocytes to produce IL-17, promoting tumor cell proliferation.