CD8A and glioblastoma: GBM tumor cells release various cytokines that contribute to the immunosuppressive milieu including IL-1/IL-6/IL-10 (suppresses activity of CD8+ and Th cells) (19–21), chemokine CCL22 (attracts CD25+ FoxP3+ regulatory T cells to the tumor niche) (22, 23), and TGF-β (facilitates epithelial−to−mesenchymal transition and impedes transmigration of T cells to the tumor via the downregulation of ICAM expression on the endothelial cell surface) (24–26).