Inhibition of neutrophil apoptosis by hypoxia.
Freshly isolated human peripheral blood neutrophils were incubated at 5 × 106 cells/mL in atmospheres containing 21% (open bars) or 3% oxygen (gray bars). At the time points indicated, cells were recovered and apoptosis was assessed (A) by morphologic examination of cytocentrifuge preparations, (B) by flow cytometry of annexin V binding, or (C) by flow cytometry following propidium iodide staining. Data in panel A represent the mean ± SEM of 3 separate experiments each performed in triplicate (*P < .05, compared with time-matched controls incubated in 21% oxygen). Data in panels B and C are representative flow-cytometry histograms; identical data were obtained in 4 additional independent experiments. (D) Classic neutrophil appearances following in vitro aging under normoxia and hypoxia are shown, and apoptotic cells are highlighted by arrowheads.
