Expression of PDL-1 (R&D Systems), CD86, CD80 (eBioscence) and I-A  (MHC/H2 class II histocompatibility molecules; BD Bioscience) were analyzed using specific anti-mouse antibodies. Non-specific fluorescence was measured using specific isotype monoclonal antibodies and GBM cells as negative control. Pericytes death was determined using (LIVE/DEAD Fixable Blue Dead Cell Stain Kit, ThermoFisher). Stained cells were analyzed by flow cytometry using a FACS Canto II Flow cytometer (BD Bioscience) and data were analyzed with Kaluza analysis software (Beckman Coulter, Fullerton, CA).