CD8A and glioma: During the first steps of glioma development, competent immune cells, like microglia, natural killer (NK) cells, macrophages, and dendritic cells (DCs), try to impair tumor growth through the release of cytotoxic and proinflammatory factors TNF-α and IL-6, which recruit T CD4+ helper and T CD8+ cytotoxic cells from the periphery to the tumor.