Increased Levels of Circulating Monocytic- and Early-Stage Myeloid-Derived Suppressor Cells (MDSC) in Acute Myeloid Leukemia

To investigate the levels of circulating myeloid-derived suppressor cells (MDSC) in patients with primary acute myeloid leukemia (AML), and to explore the relationship between the number of MDSC and AML.Peripheral blood samples from 29 patients with primary AML and 30 healthy controls were collected. CD33, CD11b, HLA-DR, CD14, and CD15 were used to label cells, and flow cytometry was used to analyze the numbers of total MDSC and subgroups eMDSC (early-stage MDSC), M-MDSC (monocytic MDSCs), PMN-MDSC (polymorphonuclear-MDSCs) or G-MDSC (granulocytic-MDSC) via two gating strategies. Presence of MDSC in AML was determined after assessment of clinical data.Phenotypic analysis of MDSC by the two gating strategies was consistent. Compared with healthy controls, the numbers of total MDSC (CD33+CD11b+ HLA-DR-) and G-MDSC (CD33+CD11b+ HLA-DR-CD14¬-CD15+ or CD14¬-CD15+ CD11b+) in peripheral blood of AML patients were lower (p < 0.05), while numbers of M-MDSC (CD33+CD11b+ HLA-DR-CD14+CD15- or HLA-DR-/LOWCD14+) and eMDSC (CD33+CD11b+ HLA-DR-/LOWCD14-CD15-) were higher (p < 0.05). The levels of G-MDSC in peripheral blood of AML-M2 patients were higher than those in other subtypes, along with total MDSC, while the levels of eMDSC and M-MDSC in AML-M3 patients were higher than those in other subtypes.The high frequency of HLA-DR-/LOWCD14+M-MDSC and CD33+CD11b+ HLA-DR-/LOWCD14-CD15- eMDSC in peripheral blood of AML patients indicates potential for MDSC as a diagnostic index in AML.