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The Immune System’s Weirdest Weapon

Maybe it’s their short life span; maybe it’s the fact that they’re the main ingredient in pus. For whatever reason, neutrophils have a history of being slandered as inessential grunts. They are by far the most abundant white cells in the blood, among the first immune cells to sally forth into battle, and among the first to perish in the fight that follows. They are, by definition, dispensable, replaceable, and almost absurdly common, noted more by biologists for their propensity to die than for the roles they play in keeping us alive.

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Featured

 Neutrophils: New insights and open questions

Here, we review how neutrophils traffic to sites of infection or tissue injury, how they trap and kill bacteria, how they shape innate and adaptive immune responses, and the pathophysiology of monogenic neutrophil disorders.

 Surprise Finding Shows That Neutrophils Can Be Key Antitumor Weapons

The results were especially surprising because prior studies have shown that neutrophils around a tumor often act as allies of the tumor—the tumor co-opts them to help it survive and spread, which they do in part by suppressing other elements of antitumor immunity.

 What are neutrophils and what do they do?

When there is an infection or another source of inflammation in the body, special chemicals alert mature neutrophils, which then leave the bone marrow and travel through the bloodstream to the site in need. Unlike some other cells or blood components, neutrophils can travel through junctions in the cells that line blood vessel walls and enter into tissues directly.

Articles of Interest

The Neutrophil’s Role During Health and Disease

Neutrophils have always been considered as uncomplicated front-line troopers of the innate immune system equipped with limited proinflammatory duties. Yet recently, the role of the neutrophil has been undergoing a rejuvenation of sorts. Neutrophils are now considered complex cells capable of a significant array of specialized functions, and as an effector of the innate immune response...

Neutrophil disorders

If you have a neutrophil disorder it means that you can’t fight infections as well as people with normal levels of functioning neutrophils. Some neutrophil disorders affect both males and females, and the severity of the condition can vary. From an early age, patients may have severe, recurrent bacterial and fungal infections, such as pneumonia, meningitis, sepsis and abscesses.

Neutrophil Disorders: Peds

Historically, the management and treatment options for patients with neutropenia were limited to antibiotics. However, since the advent and approval of granulocyte colony stimulating factor (G-CSF) in the 1990s, G-CSF has played a major role in the management of patients with neutropenia.

Neutrophil: A Cell with Many Roles in Inflammation or Several Cell Types?

Neutrophils are the most abundant leukocytes in the circulation, and have been regarded as first line of defense in the innate arm of the immune system. They capture and destroy invading microorganisms, through phagocytosis and intracellular degradation, release of granules, and formation of neutrophil extracellular traps after detecting pathogens. Neutrophils also participate as mediators of inflammation.

Neutrophilia

Neutrophilia is defined as a higher neutrophil count in the blood than the normal reference range of absolute neutrophil count. Neutrophilia can be seen in infections, inflammation, and/or neoplastic processes. Further evaluation is often necessary.

Neutrophils in chronic inflammatory diseases

Neutrophils are normally the first responders to acute inflammation and contribute to the resolution of inflammation. However, in chronic inflammation, the role of neutrophils is less well understood and has been described as either beneficial or detrimental, causing tissue damage and enhancing the immune response. Emerging evidence suggests that neutrophils are important players in several chronic diseases, such as atherosclerosis, diabetes mellitus, nonalcoholic fatty liver disease and autoimmune disorders.

Neutrophils in COVID-19: Not Innocent Bystanders

Neutrophils are the first responders to infection and extravasate rapidly from the blood vessels into tissue. They are the most abundant leukocyte in blood, with about 1011 neutrophils produced by the bone marrow each day, representing 40-60% of circulating immune cells in healthy adults. Neutrophils kill pathogens using oxidative burst, degranulation, phagocytosis and the release of neutrophil extracellular traps (NETs). Their role is most prominent in bacterial infection but they can also contribute to antiviral immunity.

Neutrophils: Underestimated Players in the Pathogenesis of Multiple Sclerosis (MS)

Neutrophils are the most abundant circulating and first-responding innate myeloid cells and have so far been underestimated in the context of multiple sclerosis (MS). MS is the most frequent, immune-mediated, inflammatory disease of the central nervous system. MS is treatable but not curable and its cause(s) and pathogenesis remain elusive.

The Role of Neutrophils in the Immune System: An Overview

Neutrophils, also known as polymorphonuclear leukocytes (PMNs), have long been considered as the short-lived, nonspecific white cells that form pus—and also happen to kill invading microbes. Indeed, neutrophils were often neglected (and largely not considered) as immune cells. This historic view of neutrophils has changed considerably over the past several decades, and we know now that, in addition to playing the predominant role in the clearance of bacteria and fungi, they play a major role in shaping the host response to infection and immune system homeostasis.