what are white blood cells (WBC) and its types ?

White blood cells, also known as leukocytes. The white blood cell is an important element of your blood system, which is also made up of red blood cells, plasma, and platelets. White blood cells are the part of body immune system. They help the body fight infection and other several diseases.  They move throughout your body in your blood, looking for invaders. And your body is constantly making a fresh supply.

White blood cells that are made in the bone marrow and stored in your blood and lymph tissues.

white blood cells bone marrow

White blood cells development process

A blood stem cell goes through some steps to create a red blood cell, platelet, or white blood cell.

White blood cells development process

Types of white blood cells

There are three main types of white cell in the blood:

  1. Polymorphonuclear white cells or granulocytes (so-called because they have granules present); there are three forms of Polymorphonuclear white cell – neutrophils, eosinophils, and basophils
  2. Lymphocytes
  3. Monocytes

The Polymorphonuclear cells and the monocytes (like the red cells) are formed in the red marrow of the bones, while lymphocytes are produced in the spleen and the lymph glands. The main function of the white cells is to help define the body against the infection. The polymorphs and the monocytes move towards the site of infection and engulf bacteria.

The lymphocytes act in two ways. Lymphocytes produce antibodies to counteract bacterial toxins and T-lymphocytes destroy foreign cells by direct contact. The T-lymphocytes are sub-classified into T4 (helper) cells and T8 cells according to their main function.

The normal total white cell count varies between 5000 and 10,000 per mm3 in an adult. The polymorphonuclear cells form 65% of this total, the lymphocytes 30% and the monocytes 5%. In most bacterial infection, the white blood cells count increases, sometimes to more than 20,000. This is known as leucocytosis and shows that the body is responding to overcome the infection.

A reduction of white cells below normal is called a leucopenia and occurs in certain infections such as typhoid fever or tuberculosis, probably due to a toxic effect on the marrow itself. When the number of polymorphs is greatly or even completely suppressed the condition is known as agranulocytosis. This is usually due to the toxic effect of certain drugs.

A normal white blood cells count

According to the University of Rochester Medical Center (UMRC), these are the normal ranges of white blood cells (WBC) per microliter of blood (MCL):

Age rangeWBC count (per mcL of blood)
newborns9,000 to 30,000
children under 26,200 to 17,000
children over 2 and adults5,000 to 10,000

These normal ranges can vary by lab. Another general measurement for the volume of blood is the cubic millimeter or mm3. A microliter and cubic millimeter equal the same amount.

The types of cells which make up white blood cells generally fall within a normal percentage of your overall white blood cell (WBC) count.

The normal percentages of the types of white blood cells (WBCs) in your overall count are generally in these ranges, according to the Leukemia and Lymphoma Society (LLS):

Type of WBCNormal percentage of overall WBC count
lymphocyte55 to 73 percent
neutrophil20 to 40 percent
eosinophil1 to 4 percent
monocyte 2 to 8 percent
basophil0.5 to 1 percent

Lower or higher numbers of white blood cells (WBCs) than normal can be a signal of an underlying condition.

Having a lower or higher percentage of a certain type of white blood cell can also be a sign of an underlying condition.

Symptoms of an abnormal WBC count

The signs of a low WBC count include:

  • body aches
  • fever
  • chills
  • headaches

High white blood cell (WBC) counts do not often cause symptoms, although the underlying conditions causing the high count may cause their own symptoms.

How to prepare for a WBC count?

A white blood cell (WBC) count needs no specific preparation. You basically schedule an appointment with your doctor or at a local medical laboratory.

Certain medications can interfere with your lab results and either lower or increase your white blood cell (WBC) count. The drugs that may affect your medical test results include:

  • corticosteroids
  • quinidine
  • heparin
  • clozapine
  • antibiotics
  • antihistamines
  • diuretics
  • anticonvulsants
  • sulfonamides
  • chemotherapy medication

Prior to having your blood drawn, tell your doctor about all instruction and nonprescription medications that you’re currently taking.

The symptoms of a low white blood cells count may prompt your doctor to recommend a white blood cell count. It is also normal for doctors to order a CBC and check your white blood cell count during an annual physical examination.

Understanding the test results of a white blood cells count

Abnormal test results are categorized by numbers that are higher or lower than the normal range for your age.

A low or high white blood cell count can point to a blood disorder or other disease. To identify the exact cause of a high or low WBC count, your doctor will take some factors into consideration, such as your list of current symptoms, medications and your medical history.

Leukopenia is the medical term used to describe a low WBC count. A low range can be triggered by:

  • HIV
  • autoimmune disorders
  • bone marrow disorders
  • lymphoma
  • severe infections
  • liver and spleen diseases
  • lupus
  • radiation therapy

Leukocytosis is the medical term used to define a high WBC count. This can be triggered by:

  • smoking
  • tuberculosis
  • tumors in the bone marrow
  • leukemia
  • inflammatory conditions, such as arthritis and bowel disease
  • stress
  • pregnancy
  • allergies
  • asthma
  • some medications, such as corticosteroids

After diagnosing the cause of a high or low WBC count and recommending a treatment plan, your doctor will periodically recheck your WBCs.

If your WBC count remains high or low, this can indicate that your condition has worsened. Your doctor may adjust your treatment.

If your WBC count shows a normal range, this usually indicates that the treatment is working.


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