<i>E. histolytica</i> trophozoites induce the formation of human neutrophil extracellular traps.

<p>A) Human neutrophils isolated by positive selection from peripheral heparinized blood were incubated with <i>E</i>. <i>histolytica</i> HM1:IMSS trophozoites (ratio 1 amoeba to 20 neutrophils) and the release of NETs monitored with 7AAD stain at 5, 15, 30 and 60 mins. Spider web-like fibers are observed as rapid as 5 min of incubation and increase in number and density over time. The networks were initially seen projected out of neutrophils toward amoebas (5 and 15 mins), and later gradually increase in number until completely cover the trophozoites that seem to be snared in the mesh (30 and 60 mins). Neutrophils in the absence of amoebas and incubated for 60 min are shown stained with Giemsa or 7ADD.B) Incubation of isolated human neutrophils with formaldehyde-fixed trophozoites did not induce NETs at 15 and 60 min. In A and B, trophozoites location is indicated by white head-arrows; magnification 40X. C) Incubation of isolated human neutrophils with fresh trophozoites whole extract induces scarce NETs at 15 and 60 min. B and C were stained with Hoechst.