Fig. 4: DXM/lactoferrin PMN-MDSCs presented improved survival capability, less tumor homing tendency and negative tumor promotive effects compared to tumor PMN-MDSCs.

a Recovery of PBS (Con) or DXM/lactoferrin (D/L) in vitro from mouse BM cells and PMN-MDSCs from B16 tumor-bearing mice after 24, 36, and 48 h of culture in complete media without cytokines (n = 6 biologically independent samples). Purified cells (2 × 10⁵) were plated at the beginning of culture. Transfer/host PMN-MDSC ratio in spleen, PBMC, and tumor 1 (b), 2 (c) and 3 (d) days after i.v. injection of CFSE-labeled PBS (Con) or D/L in vitro from mouse spleen cells and PMN-MDSCs from B16 tumor-bearing mice into tumor-bearing recipients. Percentages of CFSE-labeled PMN-MDSC are indicated (n = 4 biologically independent animals). e IFN-γ⁺ cells in CD8 T cells from PBMC and tumor of B16 tumor-bearing mice 24 h after i.v. injection of Con PMN-MDSCs, D/L PMN-MDSCs, and tumor PMN-MDSCs. PBS was used as vehicle control. Tumor growth (f) and lung metastasis (g) after i.v. injection of Con PMN-MDSCs, D/L PMN-MDSCs, and tumor PMN-MDSCs. h Representative images of hematoxylin and eosin-stained sections of the lungs (n = 6 biologically independent animals). Error bars displayed the mean and standard deviation.