CD274 and central nervous system cancer: The infiltrating immunosuppressive immune cells mainly include myeloid-derived suppressor cells (MDSCs), M2-type macrophages (M2Mφs), regulatory T cells (Tregs) and regulatory B cells (Bregs) (40), while several inhibitory ICMs expressed in the glioma microenvironment have been reported: PD-L1 (10), galectin-1 (41), galectin-9 (42), and HVEM (15).