Neutrophil Extracellular Traps are Involved in the Innate Immune Response to Infection with Leptospira
Human neutrophils (2x105/mL) were incubated with Leptospira interrogans serovar Copenhageni (LIC) (MOI = 50) for 180 min and (A) visualized with a Nikon E200 photomicroscope or (B) fixed (PF 4%) and stained with propidium iodide (red) or with the specific marker anti-neutrophil elastase (green), and analyzed by fluorescence microscopy (n = 10). Scale bar indicates 50 μm. (C) DNA or nucleosomes were measured by fluorometry (black bars) or ELISA kit (white bars) respectively in supernatants of LICa (bacteria alone) or unstimulated neutrophils (None) (500/μL) (negative control), stimulated with PMA (50 ng/mL) (positive control), or with LIC (MOI 50, 5 or 1) for 180 min Bars represent standard error of the mean (SEM) of assays from 3–10 independent assays; ***p <0.0001 vs. None. ##p<0.01 and ####p<0.0001 vs. LIC 50.