In GBM patients, the hostile tumor microenvironment comprises, amongst other factors, interleukin (IL)-10, transforming growth factor-beta (TGF-β), and indoleamine 2,3-dioxygenase (IDO), which potently suppress the function of DC.6,8 Furthermore, this patient group is often treated with corticosteroids, mainly dexamethasone (Dex), to control cerebral edema. Here, IL10 is linked to glioblastoma.