Neutrophil apoptosis induced by IAV. Neutrophil apoptosis assessed by PI-stained hypodiploid nuclei and flow cytometry (A) and Wright-Giemsa stain to detect the morphologic characteristics of apoptotic cells (B). A total of 5 × 106/mL neutrophils were incubated with control buffer or 2, 10, and 20 μg/mL of Bangkok 79 IAV stock at 37°C. At indicated times, aliquots of each sample (1 × 106 and 1 × 105 cells for PI stain and Wright-Giemsa stain respectively) were assessed for apoptosis. Data are expressed (A) as percent of cells with hypodyploid DNA (counted 5,000 cells) or (B) as percent of cells with apoptotic characteristics with respect to the total number of cells counted (at least 400 in five different fields) and represent the mean ± SEM of at least four separate experiments. (*)Indicates where IAV significantly increased apoptosis (P ≤ .05).
