MDSCs are heterogeneous population of immature myeloid cells

that include monocytic (mMDSC) and granulocytic (gMDSC)

subsets both of which have been shown to be immunesuppressive.

Majority of studies do not distinguish between

these two subsets, however, one study provide evidence that

monocytic and granulocytic subsets not only have distinct

molecular properties and distinct gene expression profiles but

also have opposing effects on tumour cells.