Types of White Blood Cells: Overview, Function, Differences

Types of white blood cells are granulocytes (neutrophils, eosinophils, and basophils), monocytes, and lymphocytes (T cells and B cells). Keeping a count of white blood cells in the blood is part of a complete blood cell (CBC) test. Blood is also known as fluid connective tissue because it connects every cell, tissue, and organ of the body. Our blood is composed of blood plasma and blood corpuscles.

Keyterms: Blood, Granulocyte, Blood cell, Neutrophils, Eosinophils, Basophils, Monocytes, Lymphocytes, T cells, B cells, Red Blood cell, White blood cell

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Types of Blood Cells 

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For various metabolic activities, the cells of all animals and humans require oxygen and nutrients. It is also required to clean the metabolic wastes. As a result, bodily fluids circulate throughout the body as a carrier.

Circulation is the movement of bodily fluids through a specific canal. One such example of bodily fluid is Blood. The red fluid that flows through every vessel except lymph vessels is defined as blood. Red blood cells, white blood cells, platelets, and plasma make up our blood.

Our blood plasma consists of 55% of blood. It is light yellow in colour and slightly alkaline.

Coming to the blood corpuscles, the blood corpuscles consist of 45% of blood. There are two types of blood corpuscles 1) Red Blood Cells and 2) White Blood Cells. 

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White Blood Cells Relation with Granules

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Classification of White Blood Cells on the basis of presence or absence of Granules is:

1. Granulocytes 
2. Agranulocytes

Granulocytes is further subdivided into three types:

1. Neutrophils
2. Eosinophils
3. Basophils

Agranulocytes are further subdivided into two types:

1. Lymphocytes
2. Monocytes

Let’s discuss each classification in detail:

Granulocytes

Granulocytes are a type of immune cell that contains small particles called granules which also contain enzymes that are released when we have allergies, infections, and also asthma. They are subdivided into three types:

Neutrophils

• Neutrophil is 8.85 micrometer in diameter.
• Neutrophils contain very fine cytoplasmic granules. They are called polymorphonuclear cells (PMN) because they have a variety of nuclei.
• The nucleus is divided into two 3-5 lobes in neutrophils.
• The neutrophils are the cells that contain neutral granules and the nucleus of cells can be stained by using acidic or basic dyes.
• There are 3000-7000 (40-70% of WBCs) neutrophils per mm3 of blood.
• The color of granules in neutrophils is fine violet-pink in colour.
• Granules contain several enzymes such as protease, lysozymes, and myeloperoxidase. These enzymes act as a bactericidal, it breaks down bacterial cell walls.
• If the neutrophil count exceeds in our body it is known as neutrophilia, which induces pneumonia, burn, and injuries.
• Neutrophils circulate for 4-8 hrs in the body then they go in tissue where they are needed and live for 4-5 days.
• The normal value of neutrophils is 40-70% of total WBC.

Eosinophils

• Eosinophils are 12-15 micrometers in diameter.
• They have bright reddish-orange colour granules and a bilobed nucleus.
• Eosinophils constitute 2-6% of circulating WBC.
• The half-life of eosinophil is 8-18 hrs in the bloodstream. The tissue lifespan is estimated to be 2-5 days.
• Eosinophil releases enzymes during degranulation. These enzymes destroy parasites which in return eosinophil cause allergic reactions. For example: If you inhale dust particles, in response to it your body shows some allergic reaction like sneezing and red eyes. This happens due to eosinophil which reacts to foreign pathogens.
• There is 100-400 (1-4% of WBCs) eosinophil per mm3 of blood.

Basophils

• Basophils are 10-14 micrometers in diameter.
• They are bluish in colour.
• They are a granulated cell that contains histamine, heparin, and other inflammatory mediators.
• Basophil travels for 70 hrs and survives for 2-3 months in our body.

Basophil matures in the bone marrow and circulates in the peripheral as mature cells.

• Basophil nucleus is lobated.
• They play an important role in preventing blood clots.
• It provides a defense against parasitic infection.
• There are 20-50 (0-1% of WBCs) basophils in mm3 of blood.

Agranulocytes

Agranulocytes do not have granules in the cytoplasm. There are two subtypes of agranulocytes:

Lymphocytes

• The size of lymphocytes is 8 to 10 micrometers.
• The nucleus in lymphocytes is huge and there is very little place left for the cytoplasm.
• Lymphocytes are of lymphoid origin.
• They are natural cell killers.
• Lymphocytes are a part of our immune system.
• Antigens are recognized by antibodies of lymphocytes and they attach to the antigen which results in the destruction of pathogens.
• There are two types of lymphocytes: In B- lymphocytes, the humoral immunity depends on B- cells; and in T- lymphocytes, cell immunity depends on T cells.

• There are 1500-3000 (20-40% of WBCs) of lymphocytes per mm3 of blood.

Monocytes

• The size of a monocyte cell is 12 to 10 micrometers.
• They have a large kidney shaped nucleus as well as an extensive frosted glass cytoplasm.
• The word mono refers to one nucleus that monocytes have.
• This cell arises from myeloid lineage.
• Monocytes are created by a type of cell in the bone marrow known as hematopoietic stem cells.
• Monocytes move around in the bloodstream for one to three days.
• Monocytes fight against certain infections and remove dead cells and fight against cancer cells.
• They are 100-700 (4-8% of WBCs) monocytes per mm3 of blood.

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Things to Remember

• There is a famous mnemonic that says “NEVER LET MONKEYS EAT BANANA”, this is an easy way to remember types of WBCs and how much amount is needed for our human body.
• Neutrophil: (60-70%)
• Lymphocytes:( 20-40%)
• Monocytes: (3-10%)
• Eosinophils: (1-4%)
• Basophils: (1%)
• There are two types of blood corpuscles:1) RBC and 2) WBC
• The amount of WBCs in our body should be perfect, not less nor more.
• The number of Neutrophils in our body should be the highest.

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Previous Year Questions

1. Blood pressure in the pulmonary artery is​...[Neet 2016]
2. Breakdown product of haemoglobin is...[Neet 1988]
3. Bundle of His is a network of​...[Neet 2003]
4. Arteries are best defined as vessels which....[Neet 2018]
5. Arteries carry oxygenated blood except​...[Neet 1989]
6. Cells formed in bone marrow include​...[Neet 1992]
7. Compared to blood our lymph has​...[Neet 2009]
8. Blood capillaries are made of​...[Neet 1993]
9. Blood group AB has...[Neet 1991]
10. An adult human with average health has systolic and diastolic pressures as… [Neet 1998]
11. Blood pressure in the mammalian aorta is maximum during​...[Neet 2015]
12. These W.B.C.s make maximum count amongst leucocytes ?...[GUJCET 2007]
13. Which of the following are located in tunica media of human blood vessels ?...[GUJCET 2009]
14. In ECG what does T wave represent...[GUJCET 2006]
15. Closure of which of the following makes louder sound of heart beat...[GUJCET 2006]
16. The structure of which of the following consists of a layer of single cell thickness ?..[GUJCET 2007]
17. Diapedesis is...[CUCET 2007]
18. The tricuspid valve occurs between...[COMEDK UGET 2006]