Figure 4. Association between CD244 expression and functional activity of G-MDSC.

(A) Ly6G⁺CD11b⁺CD244⁺ and Ly6G⁺CD11b⁺CD244^– were sorted from spleens of EL-4 tumor-bearing mice and incubated in triplicates at indicated ratios with OT-1 splenocytes in the presence of control or OT-1-specific peptide. IFN-γ production was measured using ELISPOT assay. The values of T cell activity in the presence of control peptides were subtracted from the value obtained in the presence of specific peptides. *P < 0.05; **P < 0.01, statistically significant differences between G-MDSC and Neu. (B) ROS level was measured by flow cytometry using DCFDA staining in gated CD244⁺ and CD244^– G-MDSC isolated from spleens of EL-4 tumor-bearing mice. Numbers in the histograms show geometric MFI. Three experiments with similar results were performed. (C) MPO expression was measured by RT-PCR in sorted G-MDSC in triplicates. Two experiments with similar results were performed; **P < 0.01.