Regulation of Neutrophil Homeostasis by Spontaneous Apoptotic Death

Neutrophils are terminally differentiated and normally have a very short life-span (7- 20 hr) in circulation and in tissue (1-4 days). Neutrophil death is a critical mechanism for modulating neutrophil homeostasis. Accelerated neutrophil death leads to a decrease of neutrophil counts (neutropenia), augments the chance of contracting bacterial or fungal infections, and impairs the resolution of such infections. On the other hand, delayed death and clearance of neutrophils in tissues cause unwanted and exaggerated inflammation. Thus, the death program in neutrophils needs to be well controlled to provide a perfect balance between their immune functions and their safe clearance. In this article, we summarize recent studied on the molecular mechanism of neutrophil spontaneous death. Intracellular factors and extracellular stimuli that can modulate neutrophil lifespan as well as the involvement of neutrophil apoptosis in infectious and inflammatory diseases are also discussed