Tumor-induced MO-MDSCs phenotypically differ from their naive counterparts. (A) Values represent percentages of CD11b⁺Ly6C⁺Ly6G⁺ (PMN-MDSCs) and CD11b⁺Ly6C⁺Ly6G⁻ (MO-MDSCs) splenocytes, measured for naive mice or at various time points after tumor inoculation. For EG7 this was at 7, 14, 21, and 28 days of tumor growth. For BW-Sp3, which is a regressor/progressor model,¹²  early pro-gressors represent progressing tumors with a mean diameter of 10 plus or minus 2 mm, while late pro-gressors had a tumor diameter of 20 plus or minus 3 mm. (B) FSC/SSC plots are shown for gated CD11c⁻CD11b⁺Ly6C⁺Ly6G⁻ splenocytes from naive mice (C57BL/6 and AKR) or tumor-bearing mice (EG7 and BW-Sp3). Gate R1 represents SSC^highCD11b⁺F4/80⁺Ly6C^intCCR3⁺ eosinophils, while cells in gate R2 are SSC^lowCD11b⁺F4/80⁺Ly6C^highCCR3⁻ monocytes. Histogram plots represent expression of the indicated markers on naive gated (R1 or R2) cells compared with isotype controls (tinted). Histogram plots for R1- or R2-gated cells from tumor-bearing mice were identical (data not shown). (C) Histogram plots represent the expression of the indicated markers on gated (R2) CD11b⁺Ly6C⁺F4/80⁺CCR3⁻ monocytic splenocytes from naive or tumor-bearing mice compared with isotype controls (tinted).