Neutrophils are a type of phagocyticwhite blood cell and part of innate immunity. More specifically, they form the most abundant type of granulocytes and make up 40% to 70% of all white blood cells in humans.[1] Their functions vary in different animals.[2] They are also known as neutrocytes, heterophils or polymorphonuclear leukocytes.
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.[6]
Neutrophils are a type of phagocyte and are normally found in the bloodstream. During the beginning (acute) phase of inflammation, particularly as a result of bacterialinfection, environmental exposure,[7] and some cancers,[8][9] neutrophils are one of the first responders of inflammatory cells to migrate toward the site of inflammation. They migrate through the blood vessels and then through interstitial space, following chemical signals such as interleukin-8 (IL-8), C5a, fMLP, leukotriene B4, and hydrogen peroxide (H2O2)[10] in a process called chemotaxis. They are the predominant cells in pus, accounting for its whitish/yellowish appearance.[11]
Neutrophils are recruited to the site of injury within minutes following trauma and are the hallmark of acute inflammation.[12] They not only play a central role in combating infection but also contribute to pain in the acute period by releasing pro-inflammatory cytokines and other mediators that sensitize nociceptors, leading to heightened pain perception.[13] However, due to some pathogens being indigestible, they may not be able to resolve certain infections without the assistance of other types of immune cells.
^Ermert D, Niemiec MJ, Röhm M, Glenthøj A, Borregaard N, Urban CF (August 2013). "Candida albicans escapes from mouse neutrophils". Journal of Leukocyte Biology. 94 (2): 223–236. doi:10.1189/jlb.0213063. PMID23650619. S2CID25619835.
^De Larco JE, Wuertz BR, Furcht LT (August 2004). "The potential role of neutrophils in promoting the metastatic phenotype of tumors releasing interleukin-8". Clinical Cancer Research. 10 (15): 4895–4900. doi:10.1158/1078-0432.CCR-03-0760. PMID15297389. S2CID9782495.