Expression of both markers was significantly more frequent in higher grade tumors.19 GBM immune suppression is associated reduced circulating CD4 T cells and increased regulatory T cells (Tregs).20 PD-L1 expression by GBM cells is inducible by interferon-gamma (IFN-γ) exposure such as might occur during an antitumor immune response, therefore representing a pathway for immunosuppressive escape.21 Here, CD4 is linked to glioblastoma.