Phenotypic evaluation of the immune-suppressive subset CD11b^low/−/CD16⁻ contained within BM-MDSCs. (A) Flow cytometric analysis of CD11b^low/−/CD16⁻ cells sorted from BM-MDSCs. The expression of putative MDSCs markers, markers of mature and immature myeloid cells, and markers associated with tolerance was evaluated relative to isotype control (black histograms). In the figure is presented 1 representative of 2 independent experiments. (B) Confocal microscopic localization of MPO and ARG1 in CD11b^low/−/CD16⁻ cells, freshly isolated neutrophils, and monocytes. Scale bars = 12 μm. (C) Localization of MPO and ARG1 in CD11b^low/−/CD16⁻, CD11b⁺/CD16⁻, and CD11b⁺/CD16⁺ cells isolated from fresh BM samples determined by confocal microscopy. Scale bars = 20 μm.