CD33 and glioblastoma: MDSCs constituted about 5% of the cells within GBM tumor masses and where depicted with obvious CD33+/CD15−/CD14−/HLA-DR− negative lineage subsequent to CD33+/CD15+/CD14−/HLA-DR− neutrophilic as well as CD33+/CD15−/CD14+/HLA-DR− monocytic subtypes [29–31].