CD33 and acute graft versus host disease: For instance, common monocytic MDSCs (defined as Lin− HLA-DRlow/− CD11b+ CD33+ CD14+) (46); CD34+ monocytic MDSCs (Lin− HLA-DRlow/− CD11b+ CD33+ CD14+) (35); and early-stage MDSCs (HLA-DR−/low CD33+ CD14− CD15−) (47) were correlated with a lower incidence of acute GVHD in HLA-matched and haplo-identical HSCT settings (48).