Fig 2: Intraperitoneal Ly6G+CD11b+ population predominantly consists of CD244+ cells. The samples were collected from the MC38-based peritoneal dissemination (PD) model (n=6) as described in Fig. 2. The ratios of CD244+ cells among CD11b+F4/80−Ly6CmidLy6G+ cells were evaluated by flow cytometry. (A) Representative flow cytometric data of CD244+ cells among the CD11b+F4/80−Ly6CmidLy6G+ cells in the peritoneal cavity. (B) Time-course enumeration of the ratio of CD244+ cells among Ly6G+ cells. (C) Ratios of CD244+ cells among Ly6G+ cells in the peritoneal cavity, spleen, and peripheral blood on Day 20 after tumor inoculation. Values are expressed as mean values with standard errors. One-way ANOVA with Holm's post-hoc test was performed. *P<0.05, **P<0.01.

Fig 3: Ly6G+CD244+ cells function as PMN-MDSCs. Spleens were harvested from the MC38-based subcutaneous inoculation (SC) model at 20–30 days after tumor inoculation. Splenocytes were then purified. Ly6G+CD244+ and Ly6G+CD244− cells were further isolated from the splenocytes by a FACS Aria instrument. (A) The gene expression levels of Arginase-1 (ARG1), nitric oxide synthase 2 (NOS2), and myeloperoxidase (MPO) in Ly6G+CD244+ and Ly6G+CD244− cells were measured by quantitative real-time (q)PCR. GAPDH was used to normalize gene expression data. CFSE-labeled OT-1 splenocytes (5×105) were co-cultured with Ly6G+CD244+ or Ly6G+CD244− cells at indicated ratios with SIINFEKL peptides. CFSE fluorescence of OT-1 CD8+ T cells was measured by flow cytometry. (B) Proliferation rates of OT-1 CD8+ T cells, normalized with Ly6G+CD244− cells. (C) The total number of OT-1 CD8+ T cells. Values are expressed as mean values with standard errors. Student's t-test was performed for two group comparisons. *P<0.05, **P<0.01. PMN-MDSCs, polymorphonuclear myeloid-derived suppressor cells.