CD8A and glioblastoma: These immunosuppressive surface molecules downregulate the antitumor functions of immune cells such as cytotoxic CD8+ T and NK cells by inducing their anergy or apoptosis.10,11 Glioma tumor grade has been correlated with PD-L1 expression and degree of Treg infiltration.15–17 These data suggest an important role for PD-L1 in GBM immunosuppression, and there is considerable interest in targeting PD-L1, or its ligand PD-1, in this disease.