IL-32γ delays neutrophil apoptosis.

<p>Neutrophils were incubated with graded concentrations of IL-32γ or its vehicle. Cells were analyzed by flow cytometry for annexin V-FITC binding in conjunction with propidium iodide (PI) staining. Representative FACS analysis of neutrophils incubated for 24 hrs with vehicle (Control) or 300 ng.ml⁻¹ of IL-32γ and stained with annexin V-FITC and PI (<b>A</b>). Neutrophils were incubated with vehicle (0) or graded concentrations of IL-32γ (10, 30, 100, 300 and 1000 ng.ml⁻¹) for 24 hrs (<b>B</b>) or 48 hrs (<b>C</b>). Results are illustrated in (A) as annexin V-FITC negative and PI negative cells (non-apoptotic cells; present in the lower left quadrant of FACS), annexin V-FITC positive and PI negative cells (early apoptotic cells; lower right quadrant), annexin V-FITC positive and PI positive cells (late apoptotic cells; upper right quadrant) or annexin V-FITC negative and PI positive cells (necrotic cells; upper left quadrant). Apoptosis was also evaluated by measurement of neutrophil pan-caspase activity after 48 hrs of incubation with IL-32γ or its vehicle. Activated caspases were labelled with a FITC-conjugated pan-caspase inhibitor before being analyzed by FACS (<b>D</b>). Results represent the means ± s.e.m. of 4 different donors. Statistical significance was assessed using one-way ANOVA followed by Bonferroni multiple comparison test: means without a common letter differ (P<0.05).