CD33 and glioblastoma: Here, we analyze the presence of monocytes (evaluated as CD14+ cells), PMNs (CD15+ cells) and four myeloid-derived suppressor cell (MDSC) subsets (MDSC1, CD14+/IL4Rα+; MDSC2, CD15+/IL4Rα+; MDSC3, Lin−/HLA-DR−/CD11b+/CD33+; MDSC4, CD14+/HLA-DR−) in relapsing GBM patients, after standard treatment.