FUT4 and glioblastoma: Subsequent depletion of polymorphonuclear (PMN) -MDSCs from peripheral blood using anti-CD33/CD15-coated beads monocytic- (M-) MDSCs of glioblastoma patients increase levels of intracellular and serum S100A8/9 levels compared with M-MDSCs in healthy controls, which correlates with increased Arg1 activity in serum [13, 42].