Neutrophil granulocyte

Neutrophil granulocytes are the most abundant type of white blood cells in mammals and form an essential part of the innate immune system. In general, they are referred to as either neutrophils or polymorphonuclear leukocytes (or PMNs), and are subdivided into segmented neutrophils (or segs) andbanded neutrophils (or bands). They form part of the polymorphonuclear cell family (PMNs) together with basophils and eosinophils.^[1][2][3]

The name neutrophil derives from staining characteristics on hematoxylin and eosin (H&E) histological or cytological preparations. Whereas basophilic white blood cells stain dark blue and eosinophilic white blood cells stain bright red, neutrophils stain a neutral pink. Normally, neutrophils contain a nucleus divided into 2–5 lobes.

Neutrophils are a type of phagocyte and are normally found in the blood stream. During the beginning (acute) phase of inflammation, particularly as a result ofbacterial infection, environmental exposure,^[4] and some cancers,^[5][6] neutrophils are one of the first-responders of inflammatory cells to migrate towards the site of inflammation. They migrate through the blood vessels, then through interstitial tissue, following chemical signals such as Interleukin-8 (IL-8), C5a, fMLP andLeukotriene B4 in a process called chemotaxis. They are the predominant cells in pus, accounting for its whitish/yellowish appearance.

Neutrophils are recruited to the site of injury within minutes following trauma and are the hallmark of acute inflammation.^[7]