Figure 1.
Tumor Microenvironment
The tumor microenvironment consists of immune cells (CD8 T cells, CD4 T cells, regulatory T cells [Tregs], natural killer [NK] cells, dendritic cells, macrophages, myeloid-derived suppressor cells [MDSCs]) within the extracellular matrix, stromal cells, surrounding vascular supply, and numerous cytokines.6,113 Through expression of various cytokines (inhibitory cytokines shown by red lines, stimulatory cytokines shown by black arrows), the tumor microenvironment can promote tumor growth and immune evasion. Created with BioRender. Arg1 = arginase 1; IDO = indoleamine 2,3-dioxygenase; IL = interleukin; iNOS = inducible nitric oxide synthase; PGE2 = prostaglandin E2; R-NOS = reactive nitric oxide species; TGF = transforming growth factor; VEGF = vascular endothelial growth factor.