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Introduction to Granulocytes

IVSAT 2024

When you look at this term for the first time, you might get a little intimidated or frightened because it looks like a big and heavy word you don’t know about. Before getting too nervous about this, take a deep breath and read this article because it will simplify and allow you to understand this concept in an easy manner. In this article, we will define granulocytes, we will learn the various functions and the different types there are. 

So, let’s not waste much time and get right to it. 

Before doing anything else, we will first know what this is. 

They are a form of white blood cell that has small granules that comprise protein. They help the body fight bacterial infections and much more. There are many functions which we will look at after we define granulocytes. There are 3 kinds of white blood cells in this family. These cells are known with the aid of using their enzyme granules which grow within the cytoplasm.

When the immune system is being attacked by an infection or any other type of illness/ disease, the granulocyte releases the granules to combat the problem. The chemicals that are released by harmful substances attract the granulocytes. When they are attracted to the site, they fight the contamination by releasing their granules. They circulate through the bloodstream during their last hours of life because they have a short life span. 

The granulocyte's normal range is approximately 1.5 x 10^9 per microliter to 8.5 x 10^9 of blood. This can be affected by many things like pregnancy. Low granulocyte is called agranulocytosis and is caused by sicknesses that affect the blood, like anemia and leukemia

Before moving on, let us look at some of the granulocytes function

Granulocytes Function:

They are defensive against any microbes. They exhibit positive chemotaxis, which is critical to the annihilation of microbes. 

Another one of the granulocytes functions is that their main and topmost function is to fight bacteria. They play a key role in the immunity of the body and defend the body against any infections and illnesses. All these granulocytes, which we will look at later on, play a vital role in the safety and defense of the body against anything harmful. 

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The 4 Different Types of Granulocytes are:

  1. Neutrophils are the most common type of granulocyte. There is an abundance of these in the leukocyte found in the blood. They are the most important part of the immune system, and it plays different roles in different species. They form a guard of the body’s cellular. 

  2. Eosinophils only make up around 1% of the leukocytes. These play a vital role in the immune responses. They also play an important role in the pathogenesis of allergic diseases. 

  3. Basophils are the least common. They make up around 0.5% of the blood leukocytes and are known for antigen presentation, stimulation, and differentiation of CD4+T cells. 

  4. Mast cells are sort of granulocytes. Their granules have a lot of heparin and histamine, which both do important roles in the body. These mast cells are vital in various immune-related activities that are associated with allergies to respond to pathogens and tolerance of the immune system. 

These are the 4 types of granulocytes that you should know about quite well. Each of these is differentiated by the various chemicals that make the enzymes in its granules. These can be differentiated using a compound dye to tell the various chemical compositions. 

Fun Facts:

These white blood cells are around 12 to 15 micrometers in diameter. This means that they are bigger than red blood cells. 

The granulocyte's normal range is around 1.5 – 8.5 x 10^9/L or between 1,500 and 8,500 cells per microliter (µL) of blood.

They have a lifespan of a few days, and new ones are produced constantly by the stem cells, which are located in the bone marrow.


In this article, we learned a lot. We learned the various granulocytes function, different types, and much more. These are a very important concept and part of our body as they protect us and keep us safe from any infections, illnesses, or diseases.


Now that we know what granulocytes are, you don’t have to get worried by seeing them, and you can ace your examinations when it comes to answering questions about these. 

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FAQs on Granulocytes

1. What is the difference between granulocytes and agranulocytes?

Many times, people confuse these two, majorly because of the name, but they are very different. The differences are shown in the table below. 



1. Another name for this is polymorphonuclear leukocytes. 

2. These comprise specific granules in cytoplasm. 

3. They form a great part of the white blood cells and makeup for almost 65% of the white blood cells. 

4. These are divided into neutrophils, eosinophils, mast cells, and basophils. 

5. These come from the bone marrow and they have many lobes in their nucleus. 

1. Another name for this is mononuclear leukocytes. 

2. These are white blood cells that have no granules in cytoplasm. 

3. These only make up around 35 % of all the white blood cells.

4. These are divided into two groups which are lymphocytes and monocytes. 

5. These come from the lymph nodes and have only one lobe in their nucleus. 

2. Out of basophils, eosinophils, and neutrophil granulocytes, which is the most plentiful granulocyte in the human blood?

Granulocytes make up 65% of the white blood cells and they have thin granules. They are divided into neutrophils, eosinophils, mast cells, and basophils. The correct answer to this question is neutrophils. This is because it covers approximately 40 % – 50% of the total granulocyte count which is the most out of all the others. They are the most important part of the immune system and it plays different roles in different species. This is why, out of all the options we have; neutrophil granulocytes are the correct option and this is the most abundant granulocyte in the human blood.

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