July 21, 2020

What are Neutrophils?

Neutrophils are a type of white blood cell alongside monocytes, basophils, eosinophils and lymphocytes. They are an important part of the immune system and help to protect the body from infection. Neutrophils are one of the first cells to reach the site of infection. Just like basophils and eosinophils, neutrophils release granules from their cytoplasm to elicit an immune response, making them a type of granulocyte. Neutrophils are also a type of phagocyte in that they can engulf and absorb invading pathogens.[1]

Why take a Neutrophils blood test?

Neutrophils are responsible for preventing infection and the over or underproduction can signify the presence of infection. Therefore, an increase or decrease in neutrophil numbers can be indicative of an invading pathogen.

Neutrophils are the first white blood cells to be recruited to the site of acute inflammation. They respond to signals produced by stressed tissue cells and other immune cells like macrophages. Neutrophils, therefore, are a major early infiltration of cells in inflamed tissues and are a major component of pus.[2]

You can check your level of neutrophils together with other white blood cells within Forth’s Vitality and Ultimate blood tests.

What function do Neutrophils have in the body?

Neutrophils are the most abundant type of white blood cell in the body, accounting for up to 70% of the total white blood cell count. They have a vital role in the body’s inflammatory response because they are the first line of defence against several infectious pathogens including bacteria, fungi and protozoa.[3] The first thing neutrophils do is perform phagocytosis, where the invading pathogen is engulfed by the neutrophil into a specialised internal vacuole, called the phagosome.

Neutrophils also go through a process called chemotaxis, enabling them to move towards the site of infection or inflammation. They respond to different chemicals which stimulate their migration.

Neutrophils also congregate at the site of infection where they are attracted by cytokines expressed by macrophages, mast cells and the endothelium. Neutrophils also release cytokines which increases the inflammatory reactions from other immune cell types.

Neutrophils reach the site of injury within minutes and are a hallmark of acute inflammation.

How do changes in Neutrophils affect health and wellbeing?

Increases and decreases in neutrophils can signify infection. A low neutrophil level is called neutropenia and can be caused by a variety of infections. If neutrophil levels are already low, then you are more susceptible to infection which can leave you feeling unwell.

Neutrophilia, on the other hand, is an increase in neutrophils and is commonly caused by a bacterial infection. Neutrophils also rise when there is evidence of acute inflammation.

If you are worried about your immune levels or just want to check where you fall on the range, you can test your neutrophils level with Forth’s leading blood test service.

What can cause Neutrophils to change?

Neutrophilia is commonly caused by a bacterial infection, like conjunctivitis or impetigo. It is also caused by some viral infections such as chickenpox or herpes.[4]

Neutropenia is often caused by a viral infection such as HIV, tuberculosis or malaria. Low neutrophil levels may also be caused by certain drugs, particularly chemotherapy.

​What are the most common symptoms?

Neutrophilia itself doesn’t cause any symptoms. Instead, symptoms are caused by the infection. The most common cause is a bacterial infection, especially those which cause pus, called pyogenic infections. If neutrophilia is caused by conjunctivitis, you may experience symptoms in the eye like:

  • Bloodshot
  • Burning sensation or feeling gritty
  • Itchiness
  • Watery
  • Production of pus which sticks to the eyelashes[5]

Neutropenia doesn’t cause any symptoms, but the infection causing it can. Therefore, if the infection is caused by pulmonary tuberculosis, symptoms may include:

  • Lack of appetite and weight loss
  • Fever
  • Night Sweats
  • Fatigue
  • Persistent cough
  • Breathlessness[6]

How to keep Neutrophils in the healthy range

Neutrophils are an important part of the immune system. They work alongside other granulocytes to help fight infection. They are also key mediators in the allergic response of the body. Although you may not be able to directly influence your neutrophil count, there are some steps you can take to keep your immune system healthy.

Nutrition is an important aspect of our immune status and deficiency in some nutrients can weaken the system. It is essential to eat a healthy, balanced diet incorporating the following macronutrients:

  • zinc
  • selenium
  • iron
  • copper
  • vitamins a, c, e and b6
  • folic acid[7]

Smoking has also been implicated in damaging the immune system. Therefore, it is important to stop smoking if you currently do, particularly as the damage is reversible if you quit.[8]

Exercise is key to a healthy lifestyle. However, participating in intense exercising can cause immunodepression during recovery. One exercise bout can change the white blood cell composition and this can remain changed even during recovery. Therefore, it is essential to have enough rest between exercise sessions to prevent illness and injury.[9]


[1] PubMed Health. (2018). Neutrophils. Available at:

[2] Eberl, M and Davey, M. (2019). Neutrophils. Available at:élulas/neutrophils

[3] Mayadas, T, N., Cullere, X and Lowell, C, A. (2014). The Multifaceted Functions of Neutrophils. Annu Rev Pathol: 9, pp 181-218.

[4] Auer, R. (2007). Causes of Neutrophilia and Treatment. Available at:

[5] NHS. (2018). Conjunctivitis. Available at:

[6] NHS. (2016). Symptoms Tuberculosis (TB). Available at:

[7] Chandra, R, K. (1997). Nutrition and the Immune System: An Introduction. American Journal of Clinical Nutrition: 66, pp 460S-463S

[8] Brodin, P and Davis, M, M. (2017). Human Immune System Variation. Nature Reviews: Immunology: 17(1), pp 21-29.

[9] Peake, J, M., Neubauer, O., Walsh, N, P and Simpson, R, J. (2016). Recovery of the Immune System After Exercise. Journal of Applied Physiology: 122, pp 1077-187.

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This information has been medically reviewed by Dr Nicky Keay

Nicola has extensive clinical and research experience in the fields of endocrinology and sport and exercise medicine. Nicky is a member of the Royal College of Physicians, Honorary Fellow in the Department of Sport and Exercise Sciences at Durham University and former Research Fellow at St. Thomas' Hospital.

Dr Nicky Keay

Dr Nicky Keay

BA, MA (Cantab), MB, BChir, MRCP.