IFNG and glioblastoma: Interestingly, B7-H1 is upregulated by IFN-γ(2) and increases the proportion of CD4+FoxP3+ Tregs in healthy donor PBMCs incubated from supernatant from GBM cells, making CTL secretion of IFN-γ a double-edged sword as part of the GBM-directed immune response (38).