Neutrophil Extracellular Traps:The Biology of Chromatin Externalization

Neutrophils are essential to the homeostatic mission of safeguarding host tissues, responding rapidly and diversely to breaches of the host's barriers to infection, and returning tissues to a sterile state. In response to specific stimuli, neutrophils extrude modified chromatin structures decorated with specific cytoplasmic and granular proteins called neutrophil extracellular traps (NETs). Several pathways lead to this unique form of cell death (NETosis). Extracellular chromatin may have evolved to defend eukaryotic organisms against infection, and its release has at least three functions: trapping and killing of microbes, amplifying immune responses, and inducing coagulation. Here we review neutrophil development and heterogeneity with a focus on NETs, NET formation, and their relevance in host defense and disease. In response to specific stimuli, neutrophils extrude extracellular traps (NETs), modified chromatin structures decorated with cytoplasmic and granular proteins. NETs trap and kill microbes, amplify immune responses, and induce coagulation. In this Review, Sollberger et al. examine neutrophil development, focusing on NETs and their role in host defense and disease.