The exhaustion is mediated via myeloid-derived suppressor cells-secreted TGF-beta and IL-10, as well as M2-macrophage-secreted IDO (indoleamine 2,3-dioxygenase) [75][76]. TAMs also mediate PD-L1 expression on tumor cells via secretion of IFN-gamma. This evidence concerns the gene IFNG and neoplasm.