Singlet oxygen is essential for neutrophil extracellular trap formation

► Neutrophil extracellular traps (NETs) are pivotal for innate host defense. ► ROS contribute to NET formation but the active species are not identified. ► Singlet oxygen (1O2) scavengers inhibited Nox-dependent NET formation. ► 1O2 itself could make NETs independent of Nox activation. ► These results indicate that 1O2 is essential for NET formation.