Location, location, location: functional and phenotypic heterogeneity between tumor-infiltrating and non-infiltrating myeloid-derived suppressor cells.
An increasing number of studies is focusing on the role of myeloid-derived suppressor cells (MDSCs) in the suppression of antitumor immune responses. Although the main site of action for MDSCs is most likely the tumor microenvironment, the study of these cells has been largely restricted to MDSCs derived from peripheral lymphoid organs. Only in a minority of studies MDSCs isolated from the tumor microenvironment have been characterized. This review will give an overview of the data available on the phenotypical and functional differences between tumor-derived MDSCs and MDSCs isolated from the spleen of tumor-bearing mice or from the peripheral blood of cancer patients.
Laboratory of Molecular and Cellular Therapy; Department of Immunology-Physiology ; Vrije Universiteit Brussel ; Brussels, Belgium.
Sarah K
SK
Maenhout
Laboratory of Molecular and Cellular Therapy; Department of Immunology-Physiology ; Vrije Universiteit Brussel ; Brussels, Belgium.
Kris
K
Thielemans
Laboratory of Molecular and Cellular Therapy; Department of Immunology-Physiology ; Vrije Universiteit Brussel ; Brussels, Belgium.
Joeri L
JL
Aerts
ATRA, all-trans retinoic acid; Bv8, Bombina variagata peptide 8; CTLA-4, cytotoxic T-lymphocyte antigen-4; GM-CSF, granulocyte-macrophage colony-stimulating factor; IFN-γ, interferon gamma; IL, interleukin; IL-4Rα, interleukin-4 receptor alpha; LPS, lipopolysaccharide; M-CSF, macrophage-colony stimulating factor; MAPK, mitogen-activated protein kinases; MDSCs, myeloid-derived suppressor cells; NS cells, natural suppressor cells; PD-L1, programmed death-ligand 1; PHA, phytohemagglutinin; ROS, reactive oxygen species; TAMs, tumor-associated macrophages; Treg, regulatory T cells; VEGF, vascular endothelial growth factor.; iNOS, inducible nitric oxide synthase; immunosuppression; myeloid-derived suppressor cells; siRNA, small interfering ribonucleic acid; tumor immunology; tumor microenvironment; tumor models