White Blood Cells (WBC): Types, Function, Ranges & More

white blood cells

White Blood Cells (WBC) are also known as leukocytes that represent a crucial part of your blood stream.

They also happen to be the most viable part of the immune system and help fight against the infection and clearly defend your body against any foreign particles.

There are different types of White Blood Cells (WBC) that help in recognizing a number of harmful intruders like harmful bacteria.

In the long run, WBC produces a number of line of defence (in the form of antibodies) that eventually fight the body against future exposure to various viruses, bacteria and other harmful intruders.


What are the types of WBC?

There are a number of white blood cells found in your blood stream:

  • Eosinophils
  • Basophils
  • Neutrophils
  • Lymphocytes
  • Monocytes


Eosinophils are known to play a crucial role in fighting against infection caused by external germs or pathogens like parasites. They are best known for their role in preventing your body against any sort of allergy that may be caused by pollens.

As soon as it happens, they essentially go overboard to better mount a strong immune system against these external agents that attack your body by entering into the blood stream.

Eosinophils account for up to 5% of the entire WBC in the bloodstream. But they are found in high concentration in the digestive tract.


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Basophils are also a crucial component of your WBC that account up to 1% of the entire WBC. The role of basophils is quite important as they are known to mount a non-specific but strong immune system against pathogens. In the recent past, basophils have been found quite effective in treating asthma.

After these cells are stimulated, they are known to release histamine along with some other chemicals. This generally results in the bronchoconstriction and inflammation in the airways.



Neutrophils amount almost half of the total number of WBCs. They happen to be the first cells (line of defence) of your immune system that tend to respond against any invader (virus or bacteria) that enters into your blood stream.

Being the first responders against pathogens, they first act by sending out signals to other cells in the immune system.

After the signals reach out to other cells present in the immune system, they also start acting against the pathogens. You might have known the presence of neutrophils (high amounts) in pus as they are the primary cells present after the infection.

Please know that neutrophils can remain alive only for eight hours after they are released from the bone marrow. Talking about the numbers, almost 100 billion of them are produced on each single day by the body.



Lymphocytes are basically found in the form of B & T lymphocytes. Like other cells of the immune system, they also have a great role to play in order to invade any kind of infection or external pathogens.

For example, T cells are known to be more aggressive in their approach towards pathogens. T cells directly kill any kind of foreign bodies present in the blood.

Whereas, B Lymphocytes or B cells are responsible for providing humeral immunity as they are known to produce antibodies.

The role of antibodies (released by neutrophils upon infection) towards fighting pathogens is quite commendable as they are known to “remember” any sort of infection entering into the blood stream.

B lymphocytes play a great role in producing a variety of external vaccines. But in some cases, the role of T lymphocytes has been found quite effective, especially in fighting TB (Tuberculosis and Pertussis infection).



Do you know that monocytes are also known as the garbage trucks of your immune system? Well, it looks quite evident as they have quite a significant role to contribute among other WBCs.

Monocytes count up to 5-12% out of total number of WBCs present in your blood stream. They are actually known to migrate into tissues in order to clean up dead cells among their other crucial functions.


WBC Formation

Formation of WBC begins in the bone marrow through a process known as haematopoiesis.

wbc cells
Image Credit: sciencephoto.com | image showing apoptosis of WBC


Please note that different kind of blood cells like red blood cells, white blood cells and platelets generally descend from the stem cells that are better known as “pluripotent” or hematopoietic stem cells. They are known to differentiate or evolve in different stages during their lifetimes.

Explaining the formation of WBC, you first need to know from the beginning when the HSC (Hematopoietic stem cell) first gets separated into the lymphoid cell line via progenitor cell or myeloid stem cells. Now, these cells finally give rise to lymphocytes that are known either B lymphocytes or T lymphocytes.

There is yet another process that goes through well in the formation of these cells, especially after they originate from progenitor or myeloid stem cells.

After this happens, these cells further give rise to monocytes, neutrophils, macrophages, eosinophils and basophils. At the same time, they also tend to differentiate into the precursors of platelets and red blood cells.

The role of WBC found in the blood stream is not just limited. In other words, they are not only known to invade infection but also have to play other similar roles as well. As of now, you only know that they are required to fight against any kind of infection that enters into the blood stream by any means.

But in reality, their role is far more widespread. Their production can be enhanced due to different reasons apart from the fact when your body gets a general sort of infection.

Please know that stress also happens to be one of the reasons that primarily cause an increased WBC count. Some other reasons of an increased WBC count are:

Conditions Explaining Elevated White Blood Cell (WBC) Counts

  • General Infections
  • Cancers like lymphomas, myelomas and leukaemia where a greater number of WBCs are released into the blood stream
  • Inflammation that represent various autoimmune disorders and inflammatory bowel disorder
  • Trauma arising due to emotional or other kind of stress
  • Pregnancy- You generally come across a higher number of WBC released into the blood stream at the time of pregnancy
  • Exercise
  • Allergies and Asthma- At the time of allergies due to pollen or any other external agent, you often see an increased number of WBC released into your blood stream. They are known as eosinophils.
  • Occasions when severe infection invades the body. This is the time when the body witnesses the production of young WBCs, known as blasts. The reason why they tend to appear in the blood stream is because of the body’s attempt to produce as many of them as possible.

Conditions Explaining Low White Blood Cell (WBC) Counts

Like some other conditions related to high counts of WBC, there are conditions that may develop due to the low counts of WBC. Please take a look at some of them:

  • Severe infection
  • Bone marrow disorder or damage that may relate to the conditions like aplastic anemia, certain type of metastatic or blood cancers
  • Bone marrow damage due to a chemical or drug
  • Autoimmune disorder like lupus
  • “Sequestration” of spleen characterized by accumulation of WBC into the spleen.

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Low White Blood Count Symptoms

It’s quite necessary to know the symptoms that arise in cases of low WBC counts. But before that, you need to understand the basic function of white blood cells.

As you might have understood by now that WBC basically help us in fighting against infections that can be in the form of any external pathogen like bacteria and virus.

Infection in the blood can also arise by various other external agents that may cause local infection that sometimes lead to a serious disease like Asthma. In any case, white blood cells are basically meant to fight against infections and protect the body against intruders.

Please take a look at the cause of symptoms in the event of low white blood cells:

  • Diarrhea
  • Fever
  • Swelling, warmth or redness in the region if infection
  • Cough
  • Frequency or pain at the time of urination
  • Blood in the stools


Do you know chemotherapy can also become one of the major causes of low WBC counts in the blood stream? Well, as per the studies done in this regard, the type of WBC that mostly gets affected due to the instances of chemotherapy is none other than neutrophils.

In fact, they are known as the first line of defence found in the blood against fighting with infections.

If you come across with low counts of neutrophils at the time of chemotherapy, it gives rise to a condition known as chemotherapy-induced neutropenia. In most cases, it is found to carry the risk of some sort of serious infection.

In cases where neutrophils count drops, then it is quite harmful for the body as it loses the capacity to fight even with non severe infections.



From a general infection to the level or stage of cancer, white blood cells (WBCs) are basically involved in so many body functions. Not only that, these particular cells may also become diseased at times.

In cases where the body becomes deficient of any one type of WBC, it may lead to a number of immunodeficiency disorders or syndromes.