CD274 and glioblastoma: The high expression of PD-L1 on MDSCs, immature dendritic cells (DCs), and plasmacytoid DCs reinforces immune suppression by impairing T cell activation.258,259 The accumulation of GAMs, comprising up to 30–50% of the GBM tumor mass, further skews the immune landscape.260 While M1 macrophages exhibit antitumor properties, M2-polarized macrophages secrete IL-10 and PD-L1, enhancing T cell dysfunction and promoting tumor progression.261