Figure 1.

Tumor infiltrating immune cells in primary tumor (left panel) and in liver metastasis (right panel). In primary uveal melanoma (UM), CD8⁺ T cells and fewer CD4⁺ T cells are present, but M2 polarized macrophages are predominant. M2 macrophages stimulate Tregs through IL-10, CCL2, and CCL17. M2 macrophages suppress CD8⁺, NK, and DC secreting TGF-beta and IL-10. In liver metastasis, CD8⁺ cells surround but do not infiltrate the tumor mass, while CD4⁺ cells are present in perivascular aggregates. Furthermore, Tregs are stimulated by TGF-beta and IL-10 produced by MDSC.