Neutrophils – Definition, Function and Blood Values
Our immune system has several components that help us protect against infection. Neutrophils are one of them, and they serve very important functions.
Neutrophils are produced in the bone marrow, have a short half-life and are one of the effector cells of the immune system par excellence.
When a microbe (pathogen) enters our body, the immune system recognizes it and sends a large number of neutrophils to the site of infection to destroy it.
Read on to find out how neutrophils work, what their function is, and what it means to have high and low normal values.
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What are Neutrophils?
By definition, neutrophils are cells of myeloid lineage characterized by the presence of granules that contain enzymes and other toxic agents involved in the defense of the body. (1)
Neutrophils are the most abundant type of white blood cell in the blood. White blood cells, also called leukocytes, are a key part of your immune system .
In fact, most of the white blood cells that lead the rapid response of the immune system are neutrophils. These cells make up 55 to 70 percent of the total circulating leukocytes in the blood.
Humans produce approximately 1 x 10-11 neutrophils per day, each circulating in the blood for hours to days and then dying.
Its shape is almost spherical, with a diameter of approximately 12-15 μm with numerous membrane projections. Due to the shape of their nucleus, neutrophils are also known as polymorph nuclear leukocytes.
Neutrophils work in acute inflammation and provide an essential defense against acute bacterial infections. Neutrophil function abnormalities are rare and affect the ability to respond to life-threatening infections.
What are they for? – Function
When a microbe enters your body or has a minor injury, substances that your body sees as foreign trigger your immune system to kick in.
Neutrophils are important because they can engulf, produce, and release chemicals capable of killing microorganisms.
In particular, neutrophils are the main cells involved in the inflammation reaction. That is why these are the main effector cells of innate immunity to infection.
Unlike other white blood cells, neutrophils are not confined to a specific area of the circulation. They can move freely through vein walls and into body tissues to immediately attack microbes.
In addition, neutrophils can release their content to the extracellular environment: what is known as NET traps. This mechanism has the function of trapping and destroying bacteria, but it also plays a role in promoting inflammation and thrombosis.
The role of neutrophils in the immune system is:
- Phagocytosis (especially opsonized microbes)
- Produce antimicrobial substances – reactive O2 species, defensins
- Promote inflammation – Chemotaxis
- Trapping microbes – by NET traps
- Other antimicrobial functions: activation of proteases
Normal, high and low values
To find out your neutrophil values, your doctor may ask you for an absolute neutrophil count (ANC).
This test can give your doctor important clues about your health. For example, help diagnose a disease, monitor an existing condition, or how your treatment is going if you are receiving chemotherapy.
An ANC is usually ordered as part of a complete blood count that measures the cells in your blood. It is important for your doctor to explain your test results to you. Results may vary depending on the person’s age, gender, heredity, or other factors.
Here is a table with high and low normal neutrophil values.
| Analysis | Normal values in adults | Low values (leukopenia and neutropenia) | High values (leukocytosis and neutrophilia) |
| White blood cells | 4,300-10,000 (4.3-10.0) white blood cells / mcL | <4,000 white blood cells / mcL | > 12,000 white blood cells / mcL |
| Neutrophils (ANC) | 1,500-8,000 (1.5-8.0) neutrophils / mcL | Leve: 1,000-1,500 neutrof/mcL Moderada: 500-1,000 neutrof/mcL Grave: <500 neutrof/mcL |
>8,000 neutrófilos/mcL |
What Causes High Neutrophil Levels?
Having a high percentage of neutrophils in the blood is called neutrophilia. This is a sign that your body has an infection. Neutrophilia can indicate a number of conditions and factors, including:
- most likely bacterial infection
- non-infectious inflammation
- injury
- surgery
- Smoking cigarettes
- high stress level
- excessive exercise
- steroid use
- heart attacks
- chronic myeloid leukemia
What Causes Low Neutrophil Levels?
Neutropenia is the term for low levels of neutrophils. Neutropenia can last a few weeks or it can be chronic. It can also be a symptom of other conditions and diseases, and it increases your risk for more serious infections.
More often, low neutrophil counts are associated with the use of certain medications. But they can also be a sign of other factors or diseases, including:
- Chemotherapy treatment
- suppressed immune system
- bone marrow failure
- aplastic anemia
- congenital disorders, such as Kostmann syndrome and cyclic neutropenia
- hepatitis A, B, or C
- VIH / PAGE
- autoimmune diseases, including rheumatoid arthritis
- leukemia
- myelodysplastic syndromes
ABSTRACT
Neutrophils are cells of myeloid lineage characterized by the presence of granules containing enzymes and other potentially toxic agents involved in host defense.
The key functions of neutrophils include phagocytosis and the degradation of foreign organisms, such as bacteria, through the activation of proteases and other molecules, as well as the generation of toxic oxygen radicals.
Neutrophils play a major role as the major inflammatory cells in many conditions and can be attracted to tissues by non-infectious stimuli such as activated complement components and inflammatory mediators.
Having high (neutrophilia) or low (neutropenia) levels of neutrophils can be an indicator of your health. That is why your doctor may send you a count test to help your diagnosis.
