ETosis: a novel cell death pathway.

The formation of extracellular traps (ETs) by neutrophils and mast cells is an important mechanism in the innate immune response. These structures consist of a chromatin-DNA backbone with attached antimicrobial peptides and enzymes that trap and kill microbes. After stimulation of neutrophils and mast cells with phorbol esters, chemoattractant peptides, or chemokines, the generation of reactive oxygen species (ROS), such as hydrogen peroxide, by NAPDH [nicotinamide adenine dinucleotide phosphate (reduced form)] oxidase initiates a signaling cascade that leads to the disintegration of the nuclear and cellular membranes and the formation of ETs. This form of cell death is neither apoptotic nor necrotic, but whether it occurs because of the oxidation of phosphatases and kinases, as in other ROS-mediated signaling cascades, remains to be elucidated. These findings implicate "ETosis" as a novel cell death pathway in leukocytes.