Extrinsic mechanisms, on the other hand, include [1] inhibitory effects exerted by regulatory cells including Treg cells, DCs, tumor-associated macrophages (TAMs), MDSCs, [2] immunosuppressive cytokines, such as transforming growth factor (TGF)-β and IL-10, and [3] interaction with major histocompatibility complex (MHC) class II-expressing NPC cells (18, 35). This evidence concerns the gene TGFB1 and nasopharyngeal carcinoma.