Revised: April 4, 2013
Accepted: April 13, 2013
Published online: May 6, 2013
Neutrophils are considered as the privates of the innate immune system. They are born in the bone marrow, migrate to the tissues where they kill putative intruders. After their job they are quickly removed from the battlefield by macrophages. This view of a predetermined pathway fitted nicely in their short lifespan of 5 h. However, recent studies indicated that their lifespan was in the order of several days. Recently, it became clear that neutrophils have functions beyond killing of pathogens. The reported half-life of 5 h is hardly compatible with those functions. Moreover, the organism actively invests in rescuing primed neutrophils from clearance by the body. It appears that their half-life is highly dependent on the method used to measure their life span. Here, we discuss the literature and show that neutrophils compartmentalize which could explain partially the differences reported for their lifespan. Moreover, the methodology to label neutrophils ex-vivo could have similar deteriorating effects on their lifespan as found for transfused red blood cells.
Core tip: The lifespan of neutrophils is very dependent on the method used to determine it. Neutrophils are stored in pools and traveling from one location to another dependent on the occurrence of inflammation or not. It appears that isolating neutrophils and labeling them shortens their lifespan considerably. Their longer lifespan enables new functions assigned to them recently.