Fig. 4

MHC-II⁻S100A9⁺ monocytes are associated with immunocompromised state in late sepsis. a–c At different intervals after CLP surgery (0, 24, and 72 h), circulating monocytes were isolated and subjected to the subsequent experiments. Counter plots with quantitative bar charts showed the proportion of MHC-II⁻S100A9⁺ monocytes at different time points after CLP operation (a). Representative confocal immunofluorescence images of S100A9⁺ monocytes in each group (Scale bar = 50 μm, 20 μm) (b). Western blotting analysis indicated the protein expression of S100A9 at various time points (c). d–g PBMCs and plasma were collected from WT mice subjected to CLP surgery across different sampling time points (0, 24, and 72 h). Histogram and quantitative bar charts indicated the percentage of CD3⁺ cells at different time points after CLP surgery (d). Counter plots with quantitative bar charts were compared the proportion of CD3⁺CD4⁺ cells between groups (e). Representative counter plots with quantitative bar plots showed CD3⁺CD4⁺Foxp3⁺ Tregs proportion at different time points (f). Quantitative bar plots showed circulating levels of IL-2, IL-4, IL-10, IFN-γ, TGF-β and the ratio of IFN-γ to IL-4 in various groups (g). Statistics were analyzed by One-way ANOVA with Tukey HSD test for comparison of two groups. Data are shown as means ± SD. ^*P < 0.05, ^**P < 0.01, ^***P < 0.001, ^****P < 0.0001. CLP cecal ligation and puncture, PBMCs peripheral blood mononuclear cells, WT wild-type, IL interleukins, IFN-γ interferon-γ, TGF-β transforming growth factor-β, DAPI 4′, 6′-diamidino-2-phenylindole, Treg regulatory T cells, MHC major histocompatibility complex, ANOVA analysis of variance, SD standard deviation