The Truth about NETs
Summary
Neutrophils are considered to be the main cells responding to the invasion of bacteria. Attracted by chemotaxis, neutrophils migrate to the site of infection. Here, bacteria get engulfed by neutrophils and killed within the phagosome by proteases and reactive oxygen species. A second strategy of neutrophils to eradicate pathogens is by secretion of high amounts of antimicrobial peptides into the external milieu. Recently, a novel mechanism of microbial killing by neutrophils is observed. In response to activating stimuli, neutrophils extrude their content leading to the formation of fiber like structures, so called neutrophil extracellular traps (NETs). The bacteria are caught and thereafter killed extracellularly by NET constituents. In this review, a complete overview is given about the knowledge of neutrophil extracellular killing so far. The composition of the NETs, even as the process underlying the formation of these structures will be discussed. Additionally, owing to the finding of NETs, some human diseases like CGD can be explained in a different way. Finally, to confirm the existence of NETs - in evolutionary point of view - bacteria should be adapted to evade extracellular killing by neutrophils to enhance their survival.