TGFB1 and glioblastoma: Moreover, CD33+ MDSC have been discovered at higher levels in the peripheral blood (PB) of GBM patients than in healthy persons, and healthy persons-derived CD14+ monocytes (MONs) exposed to GBM cells may gain MDSC-like features, like upregulating the production of immunosuppressive factors like B7-H1, IL-10, and TGF-β, and inducing apoptosis in activated lymphocytes [20].