TGFB1 and neoplasm: Tremendous studies have shown that the tumor microenvironment can act on human pDCs through immunosuppressive mediators (such as PGE2 and TGF-β [130]) or pDC regulatory receptors to inhibit or alter its functional activity, possibly leading to inhibition of IFN-α secretion or induction of Treg and preventing an effective anti-tumor response [131,132,133].