TGFB1 and neoplasm: The low-density fraction (mononuclear cell fraction) consists of at least two morphologically distinct neutrophil subsets: activated mature neutrophils (circulating N2-type neutrophils, Nc2) and immature PMN-MDSCs,74 and both subsets display pro-tumor properties.75 Mature Nc2 in the low-density fraction are derived from mature HDNs in a TGF-β-dependent manner.