Fig. 1.

Apoptosis of infected neutrophils is impaired. The ability of mid-log phase F. tularensis to prolong PMN lifespan was quantified by Annexin V-FITC/PI staining and flow cytometry. a Representative flow cytometry plots of uninfected PMNs (top row) and LVS-infected PMNs (bottom row) obtained at 3, 6, 12 and 24 h, as indicated. b Pooled flow cytometry data indicate the percentage of early apoptotic (Annexin V+/PI-) cells and late apoptotic/necrotic (Annexin V+/PI+) cells at each time point and are the mean ± SD of 6 independent experiments. *** p < 0.001; * p < 0.05. Where not visible, error bars are smaller than symbols. c Caspase-3 activity in control, LVS-infected and STS-treated PMNs at each time point measured using Caspase-Glo reagents. Data are from 1 experiment representative of 5 independent determinations. RLU = Relative light units.