Neutrophils are white blood cells and part of the immune system. They are the most common PMN (polymorphonuclear granulocytes), constituting about 99% of them. PMNs account for 70% of all leukocytes. Neutrophils are active phagocytes capable of only one phagocytic event, expending all of their glucose reserves in an extremely vigorous respiratory burst. Being highly-motile, neutrophils quickly congregate at a focus of infection. They are much more numerous than the longer-lived monocyte/macrophages. The first phagocyte a pathogen is likely to encounter is a neutrophil. Some authorities feel that the short lifetimes of neutrophils is an evolutionary adaptation to minimize propagation of those pathogens that parasitize phagocytes. The more time such parasites spend outside a host cell, the more likely they will be destroyed by some component of the body's defenses.
