Glioma cells and certain immune cells release multiple immunosuppressive factors into the TME, such as TGF-β and IL-10, which can attract and activate immunosuppressive cells (such as tumor-associated macrophages (TAMs) and Treg cells), while inhibiting the activation of APCs and effector immune cells (144, 145). This evidence concerns the gene TGFB1 and central nervous system cancer.