Emergence of neutrophils-derived monocytic cells in vivo. (A) Morphology of peritoneal lavage cells at day 1 after peritonitis induction. Leukocyte subpopulations from peritoneal lavage fluid (PLF) were FACS-sorted for Ly6G^–F4/80⁺ (R1), Ly6G⁺F4/80⁺ (R2), and Ly6G⁺F4/80^– (R3) and analyzed by May-Grünwald-Giemsa staining (bar = 10 µm). Percentages of cells were calculated (M, monocytes/macrophages; G, neutrophilic granulocytes; Eos, eosinophilic granulocytes). Representative cell morphology is shown. (B) Histomorphologic examination of GFP⁺Ly6G⁺F4/80^– neutrophils before transfer into ThG-induced mice (bar = 10 µm). FACS histograms: GFP-nonexpressing cells were gated and analyzed for the expression of TCRβ and B220. (C) Time-dependent conversion of GFP⁺Ly6G⁺F4/80^– neutrophils from G-CSF–mobilized mice to monocytelike cells in vivo. PB GFP⁺Ly6G⁺F4/80^– neutrophils were isolated from lys-EGFP mice after treatment with G-CSF (upper diagram). Peritonitis in C57BL/6J wild-type mice was induced by intraperitoneal injection of 4% ThG. GFP⁺Ly6G⁺F4/80^– neutrophils were transferred by intraperitoneal injection 4 hours postinduction of peritonitis. The phenotype of GFP⁺ cells in PLF was analyzed at indicated time points by FACS for Ly6G and F4/80 expression. Representative from 2 independent experiments are shown. (D) Histomorphologic analysis of sorted GFP⁺F4/80⁺ monocytelike cells from PLF at day 2 of peritonitis (original magnification ×20).