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The branch of biological sciences that deals with the study of the immune system including biological and physiological functioning of the immune system is called immunology.
- This study deals with how the immune system responds to foreign materials and harmful microorganisms.
- It plays an important role in identifying what types of disorders affect the immune system.
- Clinical, cancer, transplant and veterinary are the types of immunology.
Flow Chart on Immunology
What is an Immune System?
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Our immune system acts as a defense mechanism against pathogens and harmful microorganisms like bacteria, viruses, fungi, etc. An immune system is defined as the body’s defense mechanism that helps us fight against diseases and infections.
- It consists of various tissues, organs, proteins, and white blood cells (leukocytes).
- The white blood cells multiply when they see a pathogen, and send signals to other cells of the immune system.
- These cells are located in lymphoid organs, which eliminate the disease and repair the damaged tissues.
Lymphatic System
A lymphatic system is a series of organs, tissues, and vessels that protect the immune system from infections.
- This system also helps in maintaining the fluid levels of the body.
- Leukocytes in the lymphatic system travel to different organs through the vessels.
The table below shows the different organs present in the lymphatic system. These organs are termed ‘lymphatic organs’.
| Lymphatic Organs | Functions |
|---|---|
| Spleen | It is one of the largest lymphatic organs present just below the rib and above the stomach. It is responsible for removing worn-out cells and filtering the blood. |
| Bone Marrow | A soft spongy tissue is present between certain bones like the hip bone and backbone. They produce red blood cells, white blood cells, and platelets. |
| Thymus | It is located under to breastbone where T cells grow and mature. |
| Lymph nodes | Lymph nodes are the glands that remove cancer and damaged cells from the body. These nodes store white blood cells to fight against infections. |
| Tonsils | These are a type of mucosa-associated lymphoid tissue (MALT) that helps in filtering the germs that enter via the nose and mouth. |
| Appendix | It is a type of gut-associated lymphoid tissue that plays an essential role in the recovery of bacteria present in the gut. |
Cells of Immune System
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Leukocytes are the major cells present in the immune system. These cells are divided into various types that are discussed below:
Granulocytes
Granulocytes are the types of white blood cells or leukocytes that contain granules in the cytoplasm.
These are further divided into neutrophils, basophils, and eosinophils.
- Neutrophils help in fighting against infections and account for 70%.
- Basophils are the white blood cells that are produced in the bone marrow and they help fight against skin allergies.
- Eosinophils are responsible for combating infections and multicellular parasites.
Agranulocytes
These are the types of white blood cells or leukocytes which do not contain granules in the cytoplasm.
- A type of agranulocyte is the monocyte which makes up 2-8% of the body’s white blood cells.
Lymphocytes
About 20-40% of the human body is covered with Lymphocytes or lymphoid cells. They travel in the blood and also throughout the body tissues and organs. These cells are further divided into 3 types:
- B-lymphocytes
- T-lymphocytes
- Natural killer cells
B-lymphocytes
These cells are also known as B-cells and their role is to produce antibodies immunoglobulins.
- After maturing in the bone marrow, B-lymphocytes migrate to different parts of the body.
- They form antigen-binding receptors on their membrane which are called B-receptors.
T-lymphocytes
These cells are also referred to as T-cells and mature in the thymus gland.
- Similar to the B-cells, T-lymphocytes form an antigen-binding receptor called T-receptor.
- They migrate to different organs like the spleen, bone marrow, bloodstream, etc.
Natural Killer Cells
Natural Killer Cells, in short, are called the NK cells which were first discovered in 1976.
- NK cells are called granular lymphocytes.
- They play an essential role in fighting against tumor cells.
Types of Immune System
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The immune system is classified based on how it responds to an antigen (like bacteria, viruses, etc.). There are two types of immune systems namely:
- Innate Immune System
- Adaptive Immune System
Innate Immune System
The innate immune system consists of certain cells and proteins that fight with the microorganisms that cause the infection.
- This type of system functions immediately after the birth of the child.
- Phagocytic leukocytes, natural killer cells, physical epithelial barriers, and dendritic cells are the major elements of this type of system.
Adaptive Immune System
In the innate immunity system, certain cells do not respond to pathogens or invaders properly. This is when the adaptive immune system plays its role in fighting those invaders.
- This type of system functions as a person grows throughout their lives.
- B lymphocytes and T lymphocytes produce antibodies that will protect the body from infectious diseases.
Diseases of the Immune System
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Several diseases of the immune system are mentioned below:
Immunodeficiency
Immunodeficiency is a disorder in which the immune system fails to respond to antigen.
- In other words, its ability to fight against diseases is reduced or is not present.
- Severe combined immunodeficiency is an example of immunodeficiency.
Sepsis
Sepsis is a life-threatening disease in which the immune system abnormally responds to an infection resulting in poor functioning of the organs.
- This leads to septic shock.
- Kidneys, liver, lungs, etc, are damaged.
Autoimmune diseases
Autoimmune diseases are those diseases that attack our own cells instead of foreign cells.
- Examples of autoimmune diseases are Chron’s disease, Type 1 diabetes, Rheumatoid arthritis, Lupus antigen, etc.
Allergies
Allergies occur when the immune system reacts to those substances that aren’t harmful.
- The symptoms of allergies can range from mild to severe.
- Dust, pollen, and food products like nuts, dairy, and gluten are examples of allergens.
Symptoms of Immune Dysfunction
Techniques in Immunology
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Different techniques in immunology are used to study the antigen-antibody interactions. These techniques include:
- Enzyme-Linked Immunosorbent Assay
- Electrophoresis
- Counter electrophoresis
- RadioimmunoAssay
- Immunodiffusion Tests
- Isolation of Immune Cell
- ELISPOT
- Serology
Applications of Immunology
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There are various applications of immunology in the fields of medicine, bacteriology, dermatology, biotechnology, virology, etc.
- It is used in the development of new vaccines.
- It plays a vital role in organ transplantation.
- Immunology is used to identify cancerous cells in the body.
- Veterinary immunology is used to improve animal health.
Things to Remember
- The branch of medicine that deals with the study of the immune defense mechanism is called immunology.
- The first vaccine for smallpox was developed by Edward Jenner in 1796.
- Leukocytes, bone marrow, thymus, and lymphatic system are the main components of the immune system.
- Antibody technology and flow cytometry are the research tools used in immunological techniques.
- Cancer is one of the examples of immune dysfunction.
Sample Questions
Ques. What is the fundamental element of the immune system? (2 marks)
Ans. The fundamental element of the immune system is the antigen-antibody interaction.
- The immune system produces certain antibodies, these antibodies are present in response to an antigen like bacteria, viruses, or pathogens.
- When a foreign molecule enters the body, these antibodies immediately come into action to remove them from the body.
Ques. Immunology is important in transplantation. How? (2 marks)
Ans. Immunology plays an important role in organ transplantation. When a damaged organ or a tissue is replaced with a healthy one the immune system triggers.
- It identifies the transplanted organ as a foreign molecule and triggers the immune system to destroy it.
- Therefore, it is essential to understand transplantation immunology to identify the complexity of the immune system.
Ques. Mention the diseases that are treated with vaccines. (2 marks)
Ans. The diseases that are treated with vaccines are:
- Smallpox
- Measles
- Tetanus
- Polio
- Tuberculosis
- Whooping cough
- Mumps
Ques. What is the relevance of veterinary immunology? (3 marks)
Ans. Veterinary immunology deals with the study of improving animal health.
- Just like humans, animals also suffer from various infections and diseases that can be transferred to humans.
- For instance, diseases like swine flu, Lyme disease, and malaria are transmitted from animals to humans.
- In this type of immunology, every cell, organ, and tissue involved in the immune response is studied.
Ques. Write any 5 symptoms of immune dysfunction. (2 marks)
Ans. The following are the 5 symptoms of immune dysfunction:
- Improper bowel movements.
- Muscles and joint pain.
- Skin problems like hives, rashes, and eczema.
- Parasitic infections
- Cold and flu
Ques. Which cells are present in the immune system? (2 marks)
Ans. Lymphocytes are present in the immune system that help fight against infections and diseases.
- They are the white blood cells that contain the B and T cells that are capable of identifying the ‘non-self’ antigens.
- Lymphocytes also contain natural killer cells that more quickly identify internal antigens like viruses and tumors.
Ques. Differentiate between adapted and innate immunity. (3 marks)
Ans. The table below shows the difference between the two:
| Adapted Immunity | Innate Immunity |
|---|---|
| Acquires during his/her lifetime. | Present at the time of birth. |
| Also called acquired immunity. | Also called native immunity. |
| Produces a delayed response (in days) | Produces rapid response (in hours). |
| Memorizes the foreign molecules | Cannot memorize foreign molecules. |
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