Immunity and its classification

Immunity and Immune response

We do not know about the many beautiful things in the world that are interesting and fundamental. In this article, we will learn about the body's defense mechanism.

Immunity and Immune Response

There are different types of immune systems to protect the human body, just like the defense systems to protect the people of a country. For a country's overall security, police, army, navy, and intelligence officers work collectively. Similarly, for the overall safety of a person against diseases, many units collectively work as the defense system, which is called the immune system. Therefore, the human body's immune system is a system that ensures that no disease germs can enter the body and make the body sick. If the germs outside are strong, a person with weak immunity may get sick. For instance, If a criminal has a powerful weapon than the anti-crime force, the criminal may win. 

Therefore, To stay healthy, the immune system must be active.

A person's immune system helps to protect him from all kinds of diseases. When a germ invades the human body, the immune system works in different ways to inhibit the microbe and keep us safe. The immune system forms these ways that inhibit germs. The immune response can be stronger or weaker depending on genetic makeup, lifestyle, or eating habits. People can stay healthy if their immunity is strong.

Classification

White blood cells play a vital role in immunity, so it is crucial to know blood cell formation. The stem cells produce the first two types of cells through hematopoiesis in the human body.

1. Myeloid Progenitor
2. Lymphoid Progenitor

Myeloid generates the following cells

• Megakaryocyte that makes platelets,
• Erythrocyte that produces red blood cells
• Mast cell
• Myeloblast generates neutrophils, basophils, eosinophils, monocyte. Monocytes generate macrophages.

 

The lymphoid produces two types of cells. They are 

1. The killer cells, and 
2. The lymphocytes.

T cells and B cells form from Lymphocytes. Plasma cells generate from B cells. And all these cells play a vital role in immunity.

 

There are usually two types of immune systems.

1. Innate immunity
2. Adaptive immunity

Innate Immunity and Adaptive Immunity

Innate immunity

Innate immunity tends to be a lot more genetic. It is also called first-line and second-line immunity.

Innate immunity is nonspecific, meaning that if the virus or bacterium, or microbe affects the body, it will destroy all the microbes in a single mechanism of action. It gives natural immunity and life-long protection to a person.

This immunity is of two types.

• External Innate Immunity
• Internal Innate Immunity

 

External Innate Immunity

External Innate Immunity is called the first-line of defense mechanism. It prevents germs from entering the body using a variety of ways.

 1. The keratin layer of the skin prevents germs from entering the skin.

 2. Dust and various pathogens cannot enter the lungs for the Miucociliary Movement.

 3. Reflexes cause many germs to excrete through sneezing and coughing.

 4. The water in the eyes contains an enzyme called lysozyme that can destroy germs.

Internal Innate Immunity

Internal Innate Immunity is of two types.

1. Humoral
2. Cellular

Humoral:

Humoral immunity naturally resists disease inside the body. For example,

Stomach acid destroys many disease germs.

Bacteria of the intestine

Complement system

Interferon

The complement system is produced from the liver and circulates in the blood as inactive. The complement system is activated when a foreign particle or microbe attacks the body. Approximately fifty types of proteins and rupture proteins are involved in this system. It helps to kill many kinds of microbes through Phagocytosis and Inflammation process.

 

Cellular:

Different types of cells work to destroy pathogenic microbes such as Macrophages, eosinophils, natural killer cells.

 

Macrophages:

Macrophage is made up of monocytes and can detect many kinds of pathogens. It can destroy microbe by phagocytosis, stimulate cytokine to inhibit pathogens in combination with T cells resulting in inflammation. It functions in different ways in different types of organs. Various types of macrophage releasing organs include Alveolar, Kufar cells, Micro swallow, Splenic.

 

Eosinophil

Eosinophil plays a vital role in immunity. When a foreign particle enters the body, it helps to destroy germs by releasing reactive oxygen such as hypobromide, superoxide, and peroxide.

 

Killer cell

When a microbe enters the body, it attacks and destroys a cell. Then the killer cell releases cytokines and inhibits the infected cell through lysis.

General Mechanism of Innate Immunity

• Prevent microbes from entering the body through physical barriers like skin and tears.

• When a foreign particle enters the body, it raises the body temperature causing fever. This increased body heat stimulates the phagocytosis process that inhibits the microbes.

• Inhibit the growth of different types of microbes inside the body

• Activate the complement system.

• When the microbe attacks the cell, the infected cell releases interferon.  Interferon helps to activate the antimicrobial activity of the surrounding cells. 

• The glands in the body destroy microbes releasing antibacterial enzymes like lactoferrin.

• Antimicrobial enzymes inhibit microbes such as lysozyme.

• Body Destroys germs through phagocytosis.  Macrophages, monocytes, neutrophils, basophils are common phagocytes.

 

2. Adaptive immunity

When the body acquires immunity for a particular disease, it is called adaptive immunity. Adaptive immunity is specific and is not achieved by birth. It produces specific immune responses on specific pathogens.  When the bacteria invade, it inhibits the bacteria in one way, while when the virus attacks, it inhibits it in another way.

Adaptive immunity is acquired by vaccination.   It is also called the body's third line of defense mechanism. B cells and T cells play a vital role.

 

 There are two types of adaptive immunity

1. Active adaptive immunity
2. Passive adaptive immunity

Active adaptive immunity

Active adaptive immunity is achieved in two ways.  When a microbe captures the body, the body produces antibodies and B cell memory.  Later this memory and antibodies destroy this microbe.  As long as the body can retain memory, the germs can no longer cause the disease in the body.  Such as chickenpox.

 

 A vaccine may protect the body before a specific germ attack, such as polio.

 

Passive adaptive immunity

When a person gets immunity from someone, it is called passive immunity.

 Such as a baby acquire from its mother through breast milk and placenta.

 

Corona patients are diagnosed with such plasma therapy.  After the corona is infected, The patient's immune response is activated, and it generates antibodies. The patient having active antibodies can survive.  These antibodies are used to diagnose another patient through plasma. 

 

 Mechanism of adaptive immunity

Humoral immunity mechanism

When the germs of a disease enters the body and circulates in the blood, the B cell combines with the helper T cells to make antibodies that only work for that particular germ, making specific antibodies for a determined pathogen. These antibodies destroy that germ only.

 

 Cellular immunity mechanism

In this mechanism, the cell infected by the germ is inhibited. But the immune system makes sure that the healthy cells in the vicinity are safe.  When a microbe attacks a cell, the helper T cell releases the cytokine. The activated T cell arrives at the spot and inhibits the cell infected by the microbe.

 T cells work on both adaptive immunity and innate immunity.