. 2019 May 7;6:71–84. doi: 10.2147/JHC.S159693

Table 2.

Two major types of myeloid-derived suppressor cells and their immunosuppressive functions

Types	Markers in mice	Markers in human	Main factors mediating immunosuppression	Mechanisms of immunosuppression
M-MDSCs	CD11b⁺Ly6G⁻Ly6C^high	CD11b⁺CD14⁺CD15⁻HLA-DR^low/−	NO, ARG1, and cytokines such as TGF-β and IL-10	Suppress T-cell responses both in antigen-specific and nonspecific manners; production of NO and cytokines
PMN-MDSCs	CD11b⁺Ly6G^highLy6C^low	CD11b⁺CD14⁻CD15⁺HLA-DR⁻ or CD11b⁺CD14⁻CD66b⁺ or LOX-1⁺	ROS, ARG1	Suppressing immune responses primarily in an antigen-specific manner; ROS production

Abbreviations: M-MDSCs, monocytic myeloid-derived suppressor cells; NO, nitric oxide; ARG1, arginase; PMN-MDSCs, polymorphonuclear myeloid-derived suppressor cells.