Neutrophil Extracellular Traps Kill Bacteria

TLDR

Neutrophils kill bacteria by engulfing them and fusing antimicrobial granules with the phagosome. Upon activation, neutrophils release extracellular traps made of granule proteins and chromatin that bind both Gram‑positive and Gram‑negative bacteria, degrade virulence factors, and kill them; these NETs are abundant in vivo during acute inflammation such as dysentery and appendicitis, concentrating antimicrobials locally to prevent bacterial spread.

Abstract

Neutrophils engulf and kill bacteria when their antimicrobial granules fuse with the phagosome. Here, we describe that, upon activation, neutrophils release granule proteins and chromatin that together form extracellular fibers that bind Gram-positive and -negative bacteria. These neutrophil extracellular traps (NETs) degrade virulence factors and kill bacteria. NETs are abundant in vivo in experimental dysentery and spontaneous human appendicitis, two examples of acute inflammation. NETs appear to be a form of innate response that binds microorganisms, prevents them from spreading, and ensures a high local concentration of antimicrobial agents to degrade virulence factors and kill bacteria.