CD274 and glioblastoma: Microglia and TAM are also known to express PD-L1 on their surface and simultaneously promote its expression on GBM cells, which make this immune checkpoint a prime target for immunotherapy for these patients (63).Blochet al. showed that the expression of PD-L1 on glioma-infiltrating macrophages is upregulated by glioma tumor cells, which made these macrophages capable of suppressing T cell activity through IL-10 signaling.