Neutrophil

Neutrophils are a type of <a href="/facts/Phagocytosis/eBrv2XKV">phagocytic</a> <a href="/facts/White_blood_cell/vsDunUK0">white blood cell</a> and part of <a href="/facts/Innate_immune_system/lz4BpSQI">innate immunity</a>. More specifically, they form the most abundant type of <a href="/facts/Granulocyte/zsE3ldLb">granulocytes</a> and make up 40% to 70% of all white blood cells in humans. Their functions vary in different animals. They are also known as neutrocytes, heterophils or polymorphonuclear leukocytes.
They are formed from <a href="/facts/Stem_cell/qgB9dFrI">stem cells</a> in the <a href="/facts/Bone_marrow/4dfudk0H">bone marrow</a> and <a href="/facts/Cellular_differentiation/bCVqUG7w">differentiated</a> into subpopulations of neutrophil-killers and neutrophil-cagers. They are short-lived (between 5 and 135 hours, see § Life span) and highly mobile, as they can enter parts of tissue where other cells/molecules cannot. Neutrophils may be subdivided into segmented neutrophils and banded neutrophils (or <a href="/facts/Band_cell/nLpqbgAx">bands</a>). They form part of the <a href="/facts/Polymorphonuclear_cells_family/zsE3ldLb">polymorphonuclear cells family</a> (PMNs) together with <a href="/facts/Basophil/FRN1ugHk">basophils</a> and <a href="/facts/Eosinophil/yhIKA8bE">eosinophils</a>.
The name neutrophil derives from staining characteristics on <a href="/facts/Hematoxylin/BAXp4hTI">hematoxylin</a> and <a href="/facts/Eosin/wDx3lL0U">eosin</a> (<a href="/facts/H%2526E_stain/TEa26lJ7">H&E</a>) <a href="/facts/Histology/yrI90zlU">histological</a> or <a href="/facts/Cell_biology/kdIBGHub">cytological</a> preparations. Whereas <a href="/facts/Basophilic/vkh3kNHG">basophilic</a> white blood cells stain dark blue and <a href="/facts/Eosinophilic/6tKv04pV">eosinophilic</a> 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 <a href="/facts/Phagocyte/1vbsR9er">phagocyte</a> and are normally found in the <a href="/facts/Blood/03zEulkj">bloodstream</a>. During the beginning (<a href="/facts/Acute_(medical)/jvxNdA6B">acute</a>) phase of <a href="/facts/Inflammation/Ura86MIy">inflammation</a>, particularly as a result of <a href="/facts/Bacteria/wC8xSCsU">bacterial</a> <a href="/facts/Infection/182XrncP">infection</a>, environmental exposure, and some cancers, 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 <a href="/facts/Interleukin-8/evhcrTme">interleukin-8</a> (IL-8), <a href="/facts/Complement_component_5a/lFo1MSKN">C5a</a>, <a href="/facts/N-Formylmethionine_leucyl-phenylalanine/1t54SWEF">fMLP</a>, <a href="/facts/Leukotriene_B4/2c10wLfL">leukotriene B4</a>, and <a href="/facts/Hydrogen_peroxide/vju6HBIc">hydrogen peroxide</a> (H2O2) in a process called <a href="/facts/Chemotaxis/hYPRdPTk">chemotaxis</a>. They are the predominant cells in <a href="/facts/Pus/jzNHzM70">pus</a>, 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. 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 <a href="/facts/Nociceptor/f3UsD9gm">nociceptors</a>, leading to heightened pain perception. However, due to some <a href="/facts/Pathogens/axMXtV1M">pathogens</a> being indigestible, they may not be able to resolve certain infections without the assistance of other types of immune cells.

Neutrophil open-in-new

Neutrophil