CD4 and central nervous system cancer: Glioma-derived EVs exert pro-tumorigenic functions in monocytes and promote their conversion into suppressor cells involved in inhibition of activated CD4+ T cells through upregulation of suppressive cytokines, PD-L1, and lymphocyte antigen six complex (Ly6C), and downregulation of proinflammatory cytokines, MHC II, and costimulatory molecule expression (143).