In glioma tissues, only low amounts of the M1-associated pro-inflammatory cytokines IFN-γ, TNF-α, IL-2, and IL-12 were detected [88,120], while high amounts of M2-associated anti-inflammatory cytokines such as TGF-β, IL-6, and IL-10were found in these tumors, indicating an immunosuppressive TME [88,120]. Here, IL6 is linked to central nervous system cancer.