Figure 4.

No therapeutic effect of the myeloid-derived suppressor cell (MDSC) depletion on mammary tumor growth and IL-15cx treatment. Breast tumors were established by injections of 2.5 × 10⁶ neu⁺-MMC cells in the left posterior mammary fat pad of parent female FVB mice (FVB, n = 4) or Her2/neu transgenic FVBN202 mice. Tumor-bearing FVBN202 mice were treated with i.p. PBS as controls (Ctrl, n = 4), anti-Gr-1 Ab 100 µg (αGr-1, n = 4), IL-15cx 12.5 µg (IL-15cx, n = 4), or both anti-Gr-1 Ab and IL-15cx (IL-15cx+αGr-1) (n = 4). Anti-Gr-1 Ab was given i.p. at days 4, 9, and 14 (indicated by red arrows) while IL-15cx was administrated i.p. at days 5 and 10 (indicated by black arrows). (A) Growth curves of neu⁺-MMC breast tumors. (B–D) Blood was collected via tail vein bleeding from three mice per group to examine immune cells. p values mean Ctrl or αGr-1 vs IL-15cx or IL-15cx+ αGr-1. (B) Flow cytometric analysis of one representative mouse from three mice. The percentages of CD8⁺ T cells or CD11b⁺Gr-1⁺ MDSCs in total gated live peripheral blood mononuclear cells (PBMCs) were indicated. (C) Percentages of CD11b⁺Gr-1⁺ MDSCs in total gated live PBMCs. (D) Percentages of CD8⁺ cells in total gated live PBMCs. Error bars represent standard deviations. *p < 0.05, **p<0.01, and ***p < 0.001 by one-way ANOVA.