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[Immunology](https://durgical.com/en/immunology/) · [Immune cells](https://durgical.com/en/immunology/#a-cells)

# Neutrophil

- Cell

The most common white blood cell: a short-lived first responder that rushes to bacteria, eats them and dies, forming pus.

Updated 2026-11-01

## Key points

- Most abundant white cell in adult blood; nucleus with three to five lobes.
- First cell at a site of acute inflammation; drawn by IL-8 (CXCL8), C5a and leukotriene B4.
- Kills by phagocytosis, granule enzymes, reactive oxygen species (NADPH oxidase) and extracellular traps (NETs).
- Left shift: more immature band forms in the blood, typical of acute bacterial infection.
- Hypersegmented neutrophils (many lobes) point to vitamin B12 or folate deficiency.

## What it is

Neutrophils are granulocytes with a nucleus of several lobes and fine pale granules. They are the most numerous white cells in blood and the first to arrive at acute inflammation, where they engulf and kill bacteria and fungi. Too few neutrophils leave a person open to severe bacterial and fungal infection; too many usually signal infection, inflammation or stress.

## Key facts

- Origin: myeloid progenitor in the bone marrow; production is boosted by granulocyte colony-stimulating factor.
- Lifespan: hours in the blood and a few days in tissue; they die by apoptosis or at the infection site.
- Dead neutrophils, debris and fluid form pus.

## Function

- Roll, stick and squeeze out of venules toward chemical signals (chemotaxis).
- Recognize microbes directly or after opsonization by antibody or complement.
- Destroy them inside the phagosome with granule enzymes and oxidants.

## Markers

- CD15
- CD16
- CD11b/CD18 (integrin)
- Myeloperoxidase

## Clinical notes

- Neutropenia: risk of serious bacterial and fungal infection; fever with neutropenia is an emergency (chemotherapy, aplastic anemia, some drugs, severe sepsis).
- Neutrophilia: bacterial infection, inflammation, burns, acute stress, glucocorticoids, smoking and some leukemias.
- Chronic granulomatous disease: no NADPH oxidase, so catalase-positive bacteria and fungi cause recurrent abscesses.
- Leukocyte adhesion deficiency (CD18): high blood neutrophils that cannot leave vessels, no pus, delayed separation of the umbilical cord.

## In the lab

- Complete blood count with differential gives the absolute neutrophil count.
- Blood smear: band forms, toxic granulation, hypersegmentation.
- Dihydrorhodamine flow test for chronic granulomatous disease.

## Memory aid

The neutrophil is a volunteer firefighter with many-lobed helmets: first to the fire, works fast, and the ash it leaves behind is pus.

## Test yourself

Think of the answer, then tap the question to see it.

## Which white cell is the first to arrive at a site of acute bacterial inflammation?

The neutrophil.

## What does a left shift on the smear mean?

More immature band neutrophils in the blood, typically during an acute bacterial infection.

## Which vitamin deficiencies cause hypersegmented neutrophils?

Vitamin B12 and folate deficiency (megaloblastic anemia).

## Why is fever in a patient with neutropenia an emergency?

Without enough neutrophils, bacterial and fungal infections can spread quickly and become life-threatening.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/immunology/neutrophil/)

## Related

- [Monocyte and macrophage](https://durgical.com/en/immunology/monocyte-and-macrophage/)
- [Phagocytosis and the respiratory burst](https://durgical.com/en/immunology/phagocytosis-and-the-respiratory-burst/)
- [Acute inflammation: vascular and cellular events](https://durgical.com/en/immunology/acute-inflammation-vascular-and-cellular-events/)
- [Phagocyte defects: CGD, LAD, Chédiak–Higashi](https://durgical.com/en/immunology/phagocyte-defects-cgd-lad-chediak-higashi/)
- [IL-8 and the chemokines](https://durgical.com/en/immunology/il-8-and-the-chemokines/)
- [CD markers: the table to know](https://durgical.com/en/immunology/cd-markers-the-table-to-know/)

## Related conditions

- [Sepsis and septic shock](https://durgical.com/en/conditions/sepsis-and-septic-shock/)
- [Megaloblastic anaemia (B12 or folate deficiency)](https://durgical.com/en/conditions/megaloblastic-anaemia/)

[← All of immunology](https://durgical.com/en/immunology/)

Educational content on the immune system; not a treatment or individual vaccination guide and no substitute for a health professional's advice. No doses are given.

Sources: [18.4 Leukocytes and Platelets](https://openstax.org/books/anatomy-and-physiology-2e/pages/18-4-leukocytes-and-platelets) (OpenStax, Rice University (Anatomy and Physiology 2e), 2022); [Neutrophils](https://www.immunology.org/public-information/bitesized-immunology/cells/neutrophils) (British Society for Immunology, 2024); [Blood differential test](https://medlineplus.gov/ency/article/003657.htm) (MedlinePlus, U.S. National Library of Medicine, 2024); [Neutropenia - infants](https://medlineplus.gov/ency/article/007230.htm) (MedlinePlus, U.S. National Library of Medicine, 2024).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/immunology/neutrophil/