NET formation requires extracellular chloride (Cl⁻).

<p>Human peripheral neutrophils (2×10⁶ cells/well) were incubated in minimal media with or without extracellular Cl⁻, and stimulated to form NETs with PMA for 3 h. NETosis was completely inhibited in the absence of extracellular Cl⁻, as seen by (A) immunofluorescence using DAPI to counterstain DNA (blue) and anti-MPO antibody (green) to visualize NETs, and (B) quantification of released extracellular DNA (each condition done in triplicate).