The study by Yousefi et al. (2009) investigates the formation of neutrophil extracellular traps (NETs) and the role of mitochondrial DNA in this process. NETs are extracellular structures that can bind and kill microorganisms, and they are typically associated with neutrophil cell death. However, the authors demonstrate that viable neutrophils can generate NETs following priming with granulocyte/macrophage colony-stimulating factor (GM-CSF) and subsequent stimulation with toll-like receptor 4 (TLR4) or complement factor 5a (C5a). Notably, the NETs formed by living cells contain mitochondrial DNA but not nuclear DNA. The release of mitochondrial DNA is found to be ROS-dependent, suggesting that ROS play a crucial role in NET formation. Additionally, neutrophils stimulated with GM-CSF and C5a showed increased survival compared to resting neutrophils that did not generate NETs. These findings indicate that NET formation by viable neutrophils does not require cell death and does not limit their lifespan. The study highlights the importance of mitochondrial DNA in innate immunity and provides insights into the mechanisms underlying NET formation.The study by Yousefi et al. (2009) investigates the formation of neutrophil extracellular traps (NETs) and the role of mitochondrial DNA in this process. NETs are extracellular structures that can bind and kill microorganisms, and they are typically associated with neutrophil cell death. However, the authors demonstrate that viable neutrophils can generate NETs following priming with granulocyte/macrophage colony-stimulating factor (GM-CSF) and subsequent stimulation with toll-like receptor 4 (TLR4) or complement factor 5a (C5a). Notably, the NETs formed by living cells contain mitochondrial DNA but not nuclear DNA. The release of mitochondrial DNA is found to be ROS-dependent, suggesting that ROS play a crucial role in NET formation. Additionally, neutrophils stimulated with GM-CSF and C5a showed increased survival compared to resting neutrophils that did not generate NETs. These findings indicate that NET formation by viable neutrophils does not require cell death and does not limit their lifespan. The study highlights the importance of mitochondrial DNA in innate immunity and provides insights into the mechanisms underlying NET formation.