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. 2017 May 25;102(3):727–740. doi: 10.1189/jlb.5VMR1116-458RRR

Figure 1.

Figure 1

Overview of MDSC immunosuppressive mechanisms.

Under steady‐state conditions, hematopoietic stem cells (HSCs) located in the bone marrow give rise to common myeloid precursors (CMPs), which then differentiate into mature myeloid cells. During tumor progression, CMPs give rise to MDSCs, which subsequently accumulate in blood and in lymphoid organs, such as the spleen. Immunosuppressive MDSCs suppress the immune system by distinct mechanisms, including induction of Treg proliferation; production of high levels of ARG1 that depletes T cells of l‐arginine; production of high levels of ROS and nitrogen species (RNS; peroxynitrate) that lead to nitration and nitrosylation of TCR, CD8, and chemokine C(X)CRs receptors; promotion of angiogenesis; and blockade of the migration of naive CD62L+ T cells to lymphoid organs, which results in diminished expansion of effector T cells ADAM17, ADAM disintegrin, and metallopeptidase domain 17 and S100A8 and S100A9—S100 calcium‐binding proteins.