How do neutrophils protect you from fatal bacterial attacks?

Last Updated December 20th, 2021

What are neutrophils?

They are infection-fighting white blood cells that account to 55-70% of the total white blood cells in our body.  These are the cells that come into the picture when the body experiences situations such as infection, injuries, drug treatment, as well as certain genetic conditions.  They are known to block the infections that are caused by pathogens on day-to-day life.

A healthy individual is known to have around 4500 to 11000 white blood cells per mm3.  When the body experiences inflammation and redness due to an infection, certain enzymes alert the mature neutrophils.  Neutrophils from the bone marrow then travel through the bloodstream to the affected site to repair them.  It has been found that neutrophils can travel through junctions in the cells such as the lining of the blood vessel walls and can enter the tissues directly.  In this article, let us discuss the normal level of neutrophils and the factors affecting the high or low neutrophil count.

Neutrophil Count

A complete blood count is the laboratory test that is used to determine the neutrophil count.  The absolute neutrophil count is estimated to be between 2500 and 7500 neutrophils per microliter.  A condition where the neutrophil levels are below 2500 per microliter is considered to be neutropenic.  Anything less than 1000 per microliter is considered to be serious that can cause serious medical problems.

Neutrophil count that is above 7500 per microliter is called neutrophilia.  The results of the complete blood count divide the neutrophils into two categories called segmented or mature neutrophils, and immature neutrophils called the bands.

During an infection, immature neutrophils are released from the bone marrow and hence when there is an increased number of immature neutrophils present in the bloodstream, it could indicate a disease condition.

Neutrophilia types and causes

Neutrophilia can be understood by determining the functions of neutrophils.  Some of the functions of neutrophils that cause an increase in neutrophils are discussed below:

Reactive neutrophilia

This occurs due to the response of stress and infections.  Since certain hormones are responsible for releasing neutrophils from the bone marrow, during a period of stress, these hormones tend to react more aggressively and cause the bone marrow to release neutrophils in large numbers leading to this condition.

Proliferative neutrophilia

This is referred to a condition which causes an increase in the production of neutrophils in the bone marrow due to a medical condition such as acute myelocytic leukemia.


Since neutrophils travel through the junctions in the cells such as the lining of the blood vessels, in certain cases, they become demarginated and continue to circulate in the bloodstream due to infections, exercise, as well as stress.

It is believed that certain health conditions are responsible for the cause of neutrophilia and these include stress, infections, cancers such as leukemia, trauma, burns, smoking, autoimmune disorders, thyroiditis, and pregnancy.

Neutropenia types and causes

This is a medical condition where the neutrophil count falls below the normal levels of 2500 per microliter.  This condition may occur independently or can occur along with the reduction of other types of blood cells. This is called pancytopenia where red blood cells, platelets, as well as the white blood cells decrease.

Some of the condition that leads to neutropenia includes:

  • Decreased production of neutrophils from the bone marrow. This occurs when a person is suffering from a vitamin deficiency or is undergoing chemotherapy due to underlying cancer.
  • Bone marrow infiltration may occur when the bone marrow is taken over by cancerous cells.
  • Demand for neutrophils. This generally occurs when there is a high demand due to the severity of the infection.  Since the immune system becomes overwhelmed by increased demand for neutrophils, it becomes difficult to produce them by the bone marrow.
  • Reduced survivability. Certain powerful viral infections can reduce the survivability of the neutrophils and lower their count.  Another reason could be due to immune destruction when the antibodies tend to self destruct which occurs with lupus.

It has been found that certain medical conditions and therapies are responsible for the cause of neutropenia and these include radiation exposure, chemotherapy, hyperglycemia, sepsis, leukemia, typhoid fever, drug interactions, vitamin B12 deficiency, and rickettsial infections.

Testing and Diagnosis

A complete blood count is ordered in an event when a person experiences symptoms that are related to chronic illness, infection, and injury.  A CBC count can determine the levels of different white blood cells.  If there is any abnormality found, the test is generally repeated to make sure the values are correct.

If the levels are abnormal such as low or high neutrophils, then further evaluation is conducted such as peripheral smear.  This test can find specific abnormalities such as the presence of immature neutrophils in the bloodstream.  After these laboratory tests are conducted, further testing is obtained to diagnose the symptoms and these include bone marrow examination, various laboratory tests to determine the infection, as well as thyroid function test and vitamin B12 test.

During this blood test, the results may also indicate a more serious finding with respect to the number of white blood cells.  If the tests indicate an overall reduction in white blood cells, this indicates a more serious condition called leukopenia.  Let us understand what leukopenia is and what the causes are.

What Is Leukopenia?

An overall reduction in the levels of white blood cells indicates a condition called leukopenia.  This is caused by some serious health conditions such as damage to the bone marrow, iron deficiency anemia, overactive spleen, as well as cancer.  Since white blood cells are considered to be immune cells, it is important to have an adequate number of white blood cells to protect the body against infections against pathogens.  Bone marrow which is a spongy tissue found inside larger bones produce these white blood cells and store them in the lymphatic tissue and blood.  When there is a reduction in these cells, it reduces the body’s ability to fight infections actively.

Types of Leukopenia

Leukopenia is considered when one of the following conditions occurs:

  • Neutropenia – As discussed earlier, the reduction in the number of neutrophils. This is generally considered to be the most common cause of leukopenia.
  • Lymphopenia – A condition where the lymphocytes are low in numbers.
  • Granulocytopenia – Reduction in the number of granulocytes causes this condition. Granulocytes consist of neutrophils, monocytes, eosinophils, and basophils.
  • Agranulocytosis – A severe type of leukopenia that is generally related to the neutrophils.

On the contrary, when the levels of white blood cells are increased in numbers, they are called leukocytosis.

Signs and Symptoms of leukopenia

A mild case of leukopenia is not noticeable and can be determined only with a blood test.  A severe leukopenia such as neutropenia requires immediate medical treatment since it may be caused due to an underlying medical condition.  It has been understood that it is not leukopenia that causes the symptoms but an underlying infection or disease can lead to the symptoms.  These include fever accompanied by chills and headache, which is an indication for infection, weight loss, diaphoresis, skin rashes, inflammation of the lymph nodes called lymphadenopathy, splenomegaly, anemia, thrombocytopenia, urinary tract infection, liver abscess, pneumonia, etc.

Leukopenia Causes & Risk Factors

Studies have identified that leukopenia can be caused generally by two main reasons.  You can develop leukopenia if the body is destroying the white blood cells more quickly or if the bone marrow is not producing enough of them.  Some of the common causes and their risk factors are discussed below:

  • Severe infections caused by bacteria such as tuberculosis where the body uses the white blood cells at a very fast pace.
  • Certain viral infections such as malaria and HIV/AIDS can damage bone marrow, which lowers the production of white blood cells.
  • Cancers such as leukemia and Hodgkin’s lymphoma can reduce the white blood cell count.
  • Autoimmune diseases such as lupus and rheumatoid arthritis are conditions in which the immune system destroys the white blood cells.
  • Congenital disorders such as Kostmann’s syndrome or myelokathexis can cause malfunction of the bone marrow.
  • Medications including antipsychotics, antibiotics, cardiac drugs, as well as antidepressants.
  • Iron-deficiency anemia.
  • Therapies used to treat cancer such as chemotherapy and radiation therapy can destroy white blood cells.
  • Finally, malnutrition also can cause a reduction in white blood cells.

Conventional Treatments for leukopenia

Leukopenia treatment is mainly based upon the cause of the underlying condition.  Some of the conventional treatments include:

  • If a severe infection is found, IV antibiotics can be administered.
  • Vitamins, steroids, and immune suppressants can be used if a case of thrombocytopenia is discovered.
  • If it is caused due to a particular drug, alternative medications will be prescribed.
  • Underlying anemia should be treated appropriately.
  • Autoimmune diseases should be managed accordingly.
  • Hospitalization can be considered as a final resort to prevent further complications by following the standard protocols.

Natural Ways to improve white blood cells

It is a bitter fact that even a healthy individual can acquire this condition and it is not possible to prevent leukopenia.  Certain lifestyle changes can be implemented to improve the levels of white blood cells and help in treating the condition.  These include:

Diets that boost immunity

It is important to add a sufficient amount of calories, nutrients, and fluids into your diet to support the recovery process of increasing the levels of white blood cells.  You need to concentrate on consuming foods that improve immunity and reduce the inflammation such as brightly-colored fruits and vegetables, high-antioxidant foods namely leafy green veggies, berries, citrus fruits, as well as yellow-colored plant foods.

You need to add lean protein to your diet in the form of poultry, fish, and dairy products.  Healthy fats in the form of olive oil, ghee, and coconut oil should be consumed.  Probiotics are highly recommended as it is known to improve as well as activate your immunity.  Iron, zinc, and selenium containing foods should be added to provide that extra energy.  Finally, you need to drink at least 8 to 10 glasses of water to keep yourself hydrated and provide adequate fluids to your body to recover.

Maintain good hygiene

Due to the decreased levels of white blood cells, you are prone to acquire infections more often and hence you need to concentrate on being more conscious of not acquiring an infection.  Few simple instructions can help you to avoid these infections such as washing your hands regularly and particularly after visiting the washroom, public places, as well as hospitals.  You should consider wearing a face mask to protect yourself from airborne diseases, as well as pay attention to small scrapes and scratches, as they are bound to become infected due to your impaired immunity levels.

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