Types of White Blood Cells - Explained Briefly
Blood is a fluid connective tissue which supplies oxygen and the mineral resources and carries out the waste products and carbon dioxide throughout the body. It is made up of different types of blood cells, which are produced in the bone marrow. It is about 80% water and 20% solids.
Types of Blood Cells:
The blood is made up of four different types of cells:
Red blood cells (RBC)
White blood cells (WBC)
Plasma
Platelets
The composition of blood is as follows:, ~55% of plasma and ~45% of blood cells. Now we will discuss briefly about WBC.
Red Blood Cells
Red blood cells are biconcave cells, and these do not have a nucleus in humans. These cells are also called erythrocytes. RBCs have a rich iron protein called haemoglobin that gives the blood its red colour. The primary and core function of these cells is to transport oxygen from various tissues and organs of the human body.
What are White Blood Cells?
WBC is a type of blood cell which helps us to fight against diseases. These WBC are produced by stem cells in the bone marrow and it is found in the blood and lymph tissue. WBC are also called leukocytes.
The lifespan of WBC is about 13 to 20 days. After this, they are destroyed inside the lymphatic system. The normal white blood cell count in blood is 4,500 to 11,000 per microlitre.
Plasma
Plasma is the extracellular and liquid portion of blood and is transparent or pale yellow coloured. Plasma in blood contains 80–90% water, and the remaining 10% is salts, enzymes, nutrients, lipids, and hormones.
Platelets
These are tiny fragments of blood cells that facilitate the formation of clots in our bodies to stop bleeding. Platelets help repair the damage and rush towards blood vessels whenever there is any damage in them.
White Blood Cells Function
WBC are a part of the immune system, if there is a decrease in the immune power, then the body releases the WBC. The main function of these cells is to protect the body from getting affected by foreign particles. Whenever an infection or foreign particle invades the body, the WBC builds up the antibodies and attacks the germs to destroy it.
White blood cells are also known as leucocytes or leukocytes.
It helps to stimulate the production of progesterone hormone in our body.
It is essential for our reproductive systems as it helps create a network of blood vessels in the ovary.
If your body is struggling and a specific area is under attack, the white blood cells surge into the area to destroy the harmful substance and avoid illnesses.
Types of White Blood Cells and Their Function:
There are three different types of white blood cells:
1. Granulocytes:
Granulocytes are a type of WBC, which has small granules made up of proteins. These are further divided into three types, and they are:
a. Basophils: Basophils helps to provide immune responses to parasitic infections. In addition to that, it has the following functions:
Prevents blood clotting: Basophil contains a substance called heparin, which is a blood-thinning substance, this avoids clotting of blood inside the body.
Mediates allergic reactions: When an immune system is exposed to an allergen, the basophil releases a substance called histamine which helps to kill the allergens, it is well known for its role to fight against asthma.
b. Eosinophils: Eosinophils are the special cells inside the immune system which are involved in inflammatory and anti-parasitic responses.
c. Neutrophils: Neutrophils help to heal damaged tissues, it also helps to fight against bacterial or viral infections.
Difference Between Basophils, Eosinophils, and Neutrophils:
2. Lymphocytes:
The lymphocytes are further divided into three types:
B cells: The B cells are also referred to as B lymphocytes, which produce antibodies in the immune system.
T Cells: The T cells are also referred to as T lymphocytes, which helps to recognize and remove the infection-causing pathogens.
Natural Killer Cells: These cells are responsible for attacking and killing the pathogens, it also kills cancerous cells.
Difference Between B Cells and T Cells:
3. Monocytes:
Monocytes make up around 2–8% of the WBC, which helps to fight against chronic infections.
WBC Normal Range:
The WBC normal range is based on age.
What Happens When a Person has a High White Blood Cell Count?
If the WBC count increases in the body, then it may lead to the disease leukocytosis. Below are the medical conditions indicated dues to high white blood cell count:
Asthma attack
Heart attack
Rheumatoid arthritis, inflammatory bowel diseases
Leukaemia
What Happens When a Person has a Low White Blood Cell Count?
If the human body is producing lower numbers of WBC, it leads to a disease called leukopenia.
Conditions for leukopenia are as follows:
Bone marrow disorders
Vitamin B-12 deficiency
Autoimmune conditions, HIV
Hence, we can conclude that blood cells play an important role in our life. It protects our body by keeping a track of foreign bodies. They also supply oxygen to cells and tissues and provide essential nutrients. Blood cells help to keep our body clean by removing the waste products through the kidney.
FAQs on Types of White Blood Cells
1. What are the five main types of white blood cells (leukocytes) and what are their primary functions?
The five main types of white blood cells are categorised into two groups: granulocytes and agranulocytes. Each has a specialised role in the immune system.
- Neutrophils: The most abundant type, they are the first responders to infection and perform phagocytosis (engulfing bacteria and fungi).
- Eosinophils: These combat parasitic infections and are involved in allergic reactions by releasing specific enzymes.
- Basophils: The least common type, they release histamine and heparin during allergic reactions and inflammation.
- Lymphocytes: Crucial for adaptive immunity, they include B cells (which produce antibodies) and T cells (which directly kill infected cells and regulate immune responses).
- Monocytes: The largest WBCs, they transform into macrophages in tissues and perform phagocytosis on a larger scale, cleaning up cellular debris and pathogens.
2. What is the primary role of white blood cells in the body's immune system?
The primary role of white blood cells is to identify and destroy foreign invaders and abnormal cells, forming the core of the body's immune system. They constantly patrol the blood and lymphatic system, searching for pathogens like bacteria, viruses, fungi, and parasites. Once a threat is detected, they mount a coordinated attack to neutralise it, prevent illness, and help heal damaged tissues.
3. What is the key difference between granulocytes and agranulocytes?
The key difference lies in the presence or absence of visible granules in their cytoplasm when viewed under a microscope.
- Granulocytes (neutrophils, eosinophils, basophils) contain prominent cytoplasmic granules, which are sacs filled with enzymes and other chemicals used to destroy pathogens and mediate inflammation. They also have multi-lobed nuclei.
- Agranulocytes (lymphocytes, monocytes) lack visible granules in their cytoplasm. Their nuclei are typically large and spherical or kidney-shaped, not lobed.
4. What happens if the white blood cell count is too high?
A high white blood cell count, a condition known as leukocytosis, indicates that the body is fighting an infection or responding to inflammation. In many cases, it is a normal, temporary response to a threat. However, a persistently and abnormally high WBC count without a clear cause can be a sign of a more serious underlying medical condition, such as leukaemia (a type of blood cancer) or an autoimmune disorder, and requires medical investigation.
5. What are some common symptoms of having a low white blood cell count?
A low white blood cell count, or leukopenia, weakens the immune system, making a person more susceptible to infections. Common symptoms are not from the low count itself, but from the resulting infections. These include:
- Frequent fevers and chills
- Recurring infections (e.g., sinus, skin, or bladder infections)
- Mouth sores or sore throat
- Wounds that are slow to heal
- Unexplained fatigue and body aches
6. How do different types of lymphocytes, like B cells and T cells, work together to fight an infection?
B cells and T cells are the core of the body's adaptive immunity and work as a highly coordinated team. First, an antigen-presenting cell (like a macrophage) engulfs a pathogen and shows a piece of it to a Helper T cell. The activated Helper T cell then stimulates the appropriate B cell to multiply and transform into plasma cells, which produce massive amounts of antibodies. These antibodies tag pathogens for destruction. Simultaneously, the Helper T cell activates Killer T cells, which seek out and destroy the body's own cells that have already been infected by the virus or pathogen, stopping it from replicating.
7. Why does a neutrophil have a multi-lobed nucleus and granules, and how does this structure help its function?
The unique structure of a neutrophil is directly related to its role as a rapid-response immune cell. The multi-lobed nucleus provides the cell with flexibility, allowing it to squeeze through the narrow gaps in capillary walls to quickly reach a site of infection in the tissues. The granules in its cytoplasm are essentially storage packets of powerful digestive enzymes and antimicrobial proteins. When a neutrophil engulfs a bacterium (phagocytosis), these granules fuse with the vesicle containing the pathogen and release their contents, effectively destroying the invader.
8. Can a high white blood cell count be a normal response, or is it always a sign of a disorder?
A high white blood cell count is not always a sign of a disorder; it can also be a normal and healthy response. The body naturally increases WBC production to fight off an active infection or during periods of intense physical stress or inflammation. This temporary increase is a sign that the immune system is working correctly. It only becomes a concern for a potential disorder, like leukaemia, when the count is extremely high and persistent without a known infection to explain it.
9. How do phagocytic cells like neutrophils and macrophages actually engulf and destroy pathogens?
The process is called phagocytosis. First, the phagocyte (e.g., a neutrophil or macrophage) identifies and attaches to the pathogen, often one that has been tagged by antibodies. The phagocyte's cell membrane then extends and wraps around the pathogen, enclosing it in an internal vesicle called a phagosome. Next, lysosomes, which are organelles containing powerful digestive enzymes, fuse with the phagosome to form a phagolysosome. Inside this structure, the enzymes break down and completely destroy the pathogen, and the cell expels the harmless waste products.
10. What is the main difference in the roles of basophils and eosinophils in allergic reactions?
While both basophils and eosinophils are involved in allergic reactions, they play different roles. Basophils are responsible for initiating the immediate inflammatory response. They release large amounts of histamine, which causes classic allergy symptoms like vasodilation (widening of blood vessels) and bronchoconstriction. In contrast, eosinophils play more of a regulatory role. They are attracted to the site of an allergic reaction and help to modulate and reduce the inflammation caused by basophils, preventing it from becoming excessive and damaging.
