Fig. 2

Phenotypes of MDSC in human cancers. MDSC collected from tumor sites or peripheral blood from cancer patients were labeled by multiple markers, which are summarized in this figure (markers reported in pre-clinical studies were excluded). It has reached a consensus that CD14 and CD15 are universal markers for MDSC classification, leading to four phenotypes of MDSC: M-MDSC (represented as red block), PMN-MDSC (represented as orange block), early-stage MDSC (eMDSC, represented as green block), and unclassified MDSC with CD14 and CD15 undetected. HLA-DR⁻, Lin^low/−, CD33⁺, and CD11b⁺ labels are commonly used for MDSC recognition. These markers, if not detected and reported in study, were shown as null block. Some of the articles also reported markers other than the aforementioned label, and these markers are represented as pink block followed by detailed information. Each line of a certain MDSC phenotype demonstrate the label reported in a study. For example, in lung cancer, there is one study reported the recognition label of M-MDSC from tumor site while nine studies reported labels of M-MDSC from peripheral blood. Abbreviations: MDSC, Myeloid-derived suppressor cell; M-MDSC, Monocytic MDSC; PMN-MDSC, Polymorphonuclear MDSC; eMDSC, early-stage MDSC