IFNG and glioblastoma: Moreover, PD-1-deficient Tregs exhibit rapid proliferation following IL-2 administration, however, eventually become proapoptotic.43 In glioblastoma, PD-1high Tregs have been identified as a population of dysfunctional and exhausted Tregs, secreting interferon (IFN)-γ.47 Interestingly, administration of anti-PD-1 antibodies further enhanced the secretion of IFN-γ from Tregs.