As prophylaxis, G-MDSCs attenuate BMF in minor histocompatibility–mismatched C.B10 model. (A) Suppression of T-cell proliferation in vitro by G-MDSCs. BM Ly6G⁺Ly6C^low (G-MDSCs), Ly6G⁺Ly6C⁻, and Ly6G⁻Ly6C⁺ cells from C.B10 mice were sorted by flow cytometry and added to CFSE-labeled LN cells from C57BL/6 (B6) mice at 1:1 ratio for 5 days after stimulation by PMA (50 ng/mL) with ionomycin (500 μM). A representative result of duplicate experiments is shown. (B) G-MDSCs as prophylaxis for murine BMF in C.B10 model. Ly6G⁺ G-MDSCs were isolated from C.B10 donor mice and injected into BMF mice at 10 × 10⁶ G-MDSCs/mouse (BMF+Ly6G cells) in the C.B10 model at the time of LN cell infusion. (C) Mice infused with G-MDSCs (n = 13) had significantly higher WBCs, RBCs, PLTs, and total BM cells, with decreased BM CD4 and CD8 T-cell infiltration, compared with control BMF mice (n = 10) when animals were analyzed at day 14. (D) Histology of sternal sections showed that G-MDSC administration improved BM cellularity. Images of the sternums are shown at ×20 magnification. Data are displayed as means with standard errors. ∗P < .05; ∗∗P < .01; ∗∗∗∗P < .0001.