Neutrophils: Description, Count and Functions

By Dr. Amrita Chakrabarti in Bone Marrow Transplant , Haematology (Hematology) , Hematology Oncology

Jan 23 , 2024 | 4 min read

What are Neutrophils?

Neutrophils are a variety of white blood cells (leukocytes), which serve as the immune system's initial defence mechanism. White blood cells are categorised into three types: granulocytes, lymphocytes, and monocytes. Among granulocytes, neutrophils coexist with eosinophils and basophils. Collectively, these white blood cells safeguard the body against infections and injuries.

Functions of Neutrophils

Neutrophils play several crucial roles in the body's immune response, functioning as a key component of the innate immune system. Here are their primary functions:

  • Phagocytosis: Neutrophils are primarily responsible for phagocytosis, a process where they engulf and digest pathogens like bacteria and fungi. This is their most well-known function.
  • Antimicrobial substances: They release a variety of substances that have antimicrobial properties. These include enzymes like lysozyme and myeloperoxidase, which can break down the cell walls of bacteria.
  • Formation of Neutrophil Extracellular Traps (NETs): In response to certain pathogens, neutrophils can undergo a unique form of cell death called NETosis. This process releases DNA and antimicrobial proteins to form neutrophil extracellular traps (NETs), which can trap and kill pathogens.
  • Chemical signalling: Neutrophils produce chemical signals (cytokines and chemokines) that help to modulate the immune response, including attracting other immune cells to the site of infection or inflammation.
  • Regulation of inflammation: They play a role in controlling the inflammation process, either by promoting or inhibiting inflammation, depending on the signals they receive.
  • Removing debris: After phagocytosis or tissue injury, neutrophils help in cleaning up the debris, including dead cells and other waste, facilitating the healing process.
  • Interacting with adaptive immune system: Neutrophils also interact with the adaptive immune system (comprising lymphocytes), aiding in shaping a more targeted immune response.

What are Common Conditions that Affect Neutrophils?

The quantity of neutrophils in the human body must be maintained within a certain range for normal bodily functions. Deviations from this range can lead to conditions stemming from an imbalance in neutrophil levels.

These conditions include:

  • Neutropenia: This condition arises when the neutrophil count falls too low, leading to swelling and recurrent infections. Neutropenia can be triggered by various factors, including cancer treatments, autoimmune diseases, or infections.
  • Neutrophilia: Also known as neutrophilic leukocytosis, this occurs when there is an excessive number of neutrophils. Often a response to a bacterial infection, neutrophilia is characterised by the premature release of immature neutrophils from the bone marrow into the bloodstream as the body attempts to combat the infection.

What Causes a High Neutrophil Count? 

It is often a normal response for the human body to generate an increased number of neutrophils to aid in healing, particularly in situations like bone fractures or severe burns. However, if neutrophil levels do not return to normal after an injury has healed, it can present a health risk. Factors that can lead to an elevation in neutrophil counts include:

What Causes a Low Neutrophil Count? 

Neutropenia occurs when the body eliminates neutrophils at a rate faster than the bone marrow can replenish them. Factors leading to a reduced neutrophil count encompass:

What is a Normal Range for a Neutrophil Count? 

An Absolute Neutrophil Count (ANC) determines the quantity of neutrophils present in a blood sample. In a healthy adult, the typical range is between 2,500 and 7,000 neutrophils per microlitre of blood. A count exceeding 7,000 or falling below 2,500 indicates a potential risk for a neutrophil-related condition.

Tests to Check the Health of Neutrophils

Tests that evaluate the health of neutrophils include:

  • Complete blood count (CBC): This test analyses the cells in a blood sample, providing insight into the cell count within the body. A CBC is useful for diagnosing various medical conditions and serves as an indicator of overall health.
  • Absolute neutrophil count (ANC): This test measures the number of neutrophil cells in a blood sample.
  • Bone marrow biopsy: This procedure assesses cell quantity and the location of their growth within the body. It involves the removal and examination of a small sample of bone marrow. Since cell production originates in the bone marrow, a biopsy helps determine whether the body is producing an adequate amount of cells and if any specific conditions are present.

Treatments for Neutrophil Conditions 

Whether individuals are dealing with low or high neutrophil counts, various treatments are available to address the imbalance. Let's explore some common approaches:

Taking antibiotics

If an individual's neutrophil count is low, their healthcare provider may recommend antibiotic therapy. This helps prevent and treat infections, bolstering the body's defence against harmful microorganisms.

Adjusting medication

Certain medications can cause neutropenia. In such cases, healthcare providers might suggest modifying or discontinuing the use of these drugs. This adjustment aims to restore a balanced neutrophil count.

Treating underlying medical conditions

Addressing the root cause is essential for managing neutrophil counts. Treating underlying medical conditions, such as infections or chronic diseases, can positively impact neutrophil levels.

Corticosteroid therapy for autoimmune disorders

Individuals with autoimmune disorders may experience high neutrophil counts. In such instances, corticosteroids may be prescribed to regulate the immune response and reduce inflammation.

White blood cell transfusion

In certain emergencies, a white blood cell transfusion might be recommended to quickly boost the overall white blood cell count, including neutrophils.

Bone marrow transplant

In severe cases of neutropenia (low neutrophil count), a bone marrow transplant may be considered. This procedure involves replacing damaged or insufficient marrow with healthy stem cells, promoting the production of normal blood cells, including neutrophils.


Neutrophils are vital components of the immune system, playing key roles in infection defence and inflammation management. Their count, measured through various tests, is crucial for diagnosing and monitoring health conditions. To learn more about neutrophils and ensure your immune health, visit Max Healthcare. Their expert team offers comprehensive care and state-of-the-art diagnostics to keep your immune system functioning optimally. Connect with Max Healthcare today for personalised advice and advanced medical solutions.

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