Our hypothesis that GBC-PC might present similar immunosuppressive properties as TAMs, which are implicated in inhibitory anti-tumor responses, is supported by the clear upregulation of Il4ra and Il1rn gene expression in GBC-PC [24, 35]. Indeed, our results show that PDL-1, which is associated with glioblastoma progression and contribute to suppress anti-tumor T cell responses [3, 36, 37, 39], is expressed in pericytes and maintained upon GBM interaction. Furthermore, we show reduced expression of T cell co-stimulatory molecules, such as CD80 and CD86, in GBC-PC, supporting an immunosuppressive phenotype that might prevent tumor clearance. Our data confirm that brain pericytes express MHC molecules [16, 20, 21], but interestingly expression levels are drastically reduced in GBC-PC compared to PC, suggesting that the anti-tumor T cell response might be affected through inefficient antigen presentation. GBC-PC also shows impaired ability to present antigen to T cells and cell culture media from GBC-PC is enough to reduce T cell responses. In addition, T cell function in response to antigen presentation by APCs is also suppressed in the presence of GBC-PC. Therefore, these results suggest that GBC-PC could acquire suppressing properties and hinder T cell activation, contributing to tumor growth by preventing the activity of other APCs.