High frequency of myeloid-derived suppressor cells in sepsis patients, with the granulocytic subtype dominating in Gram-positive cases

Myeloid-derived suppressor cells (MDSCs) constitute a heterogeneous population of immature myeloid cells that potently suppress immune responses. They were originally identified in cancer patients and have since been reported to occur also in chronic inflammation, autoimmunity and even bacterial infections. Human MDSCs are commonly divided into monocytic (Mo-MDSCs) and granulocytic (PMN-MDSCs) subtypes. To what extent the bona fide cancer MDSCs are representative of the proposed MDSCs found in other diseases is not well known. PMN-MDSCs have previously been found to be enriched among low-density granulocytes (LDGs) in density gradient centrifuged blood.