Figure 3. Macrophages are the predominant cell type in CLP and can be classified into SPM and LPM subpopulations.

(A) Peritoneal cells were stained for flow cytometry and relative numbers of CD11b⁺F4/80⁺ macrophages, CD115^–Gr1^hi neutrophils, CD115⁺Gr1^hi monocytes, Siglec F⁺ eosinophils, CD11c⁺ DCs, and CD3⁺/CD19⁺ lymphocytes; (A) was determined as percentage of CD45⁺ cells and (B) measured as absolute cell number. Plot of n = 7 mice from 2 separate experiments. Two-way ANOVA with Sidak’s multiple-comparison test. (C) Representative gating strategy for the identification of small (SPM) and large (LPM) peritoneal macrophages in the peritoneal lavage of WT mice 22 hours after CLP or sham surgery. (D) Cytospins of SPMs and LPMs isolated from peritoneal lavage of septic mice and stained with Wright-Giemsa stain. Macrophage size was determined by ImageJ software from n = 11 animals. SPMs measured 10.9 ± 0.3 μm; the size of LPMs was 15.6 ± 0.5 μm (unpaired, 2-tailed Student’s t test). *P < 0.05; **P < 0.01.