Acquired Immunity - Immune system

An ability of the immune system to adapt itself to disease and to generate pathogen-specific immunity is termed as acquired immunity and also known as adaptive immunity.

In innate immunity, the immune system blocks the entry of all the microorganisms and tuned to remember the various diseases it has faced over time and respond in a manner specific to each disease. The line of division between the innate and adaptive immunity is that the innate immune system is composed of primitive bone marrow cells that recognize foreign substances and reacting to them, whereas the adaptive immunity consists of an advanced lymphatic defense system functions by recognizing the own body cells and not reacting to them.

Acquired Immunity

Acquired Immunity

In this immune system, our body identifies the pathogens which have encountered in the past. The acquired immunity is also called as adaptive immunity. It is mainly caused when a person comes in contact with the pathogen or its antigen. Antigens are the generator of antibodies.

Our body starts producing antibodies to engulf the pathogen and destroy its antigen. When it encounters for the first time, it is called a primary response. Once a body gets used to this pathogens, antibodies are ready to attack them for the second time and are known as naturally acquired immunity.

Vaccinating pathogenic microorganisms into our body deliberately produces a similar response and is termed as artificially acquired immunity.  Immunization is a process providing resistant to pathogenic microbes and other infectious diseases by the administration of a vaccine into the body.   By immunization, it stimulates the body’s immune system to protect against subsequent infection or disease.

Cells of the Acquired immune system

Cells of the Acquired immune system

Acquired immunity comprises two special cells called B-lymphocytes and T-lymphocytes.

  • B-lymphocytes or B cells 

In the case of an infection, the adaptive immune response is characterized by the B-lymphocytes producing huge amounts of proteins called Antibodies.

  • T-lymphocytes or T-cells.

These cells are developed from stem cells in the bone marrow and get matured in the thymus gland which is found in the chest. Hence these cells are named as T cells.

Functions of T cells

  • Activation of B cells.
  • Signaling growth in all cells.
  • Helps the B-cells with the production of protein
  • Activates the cells to fight against the foreign substances.
  • They play a vital role in the destruction of all infected cells including the with a virus, or cells with DNA damage.

This antibody protein consists of four chains of peptide molecules, two small chains called light chains and other two called the heavy chains.

Acquired Immunity

Types of acquired immune response

  • Humoral immune response:

The antibodies produced by B-lymphocytes are present in the blood and they are transported all over the body. This is why it is called the humoral immune response as it consists of an antibody army produced by the lymphocytes.

  • Cell-mediated immune response:

The T-lymphocytes are responsible for this immunity. Cell-mediated immunity becomes clear in the case of transplant patients. When one of our sense organs malfunctions, we can transplant and replace the malfunctioning organs with it. But it is not that simple with the immune response.  It appears that T-lymphocytes are capable of recognizing whether a tissue or an organ is from our body or someone else’s. This is the reason why we cannot transplant and implant the organs into our body even if we find the donor with the same blood group, our body might reject the transplant. The T-cells quickly recognize that the tissue or an organ as a foreign and do not allow it to become a part of the body. This is why transplant receivers have to take immune-suppressant medication for the rest of their lives. This response is controlled by the T-lymphocytes.

The T-cells quickly recognize the foreign tissue and do not allow it to become a part of the body. This is why transplant receivers have to take immune-suppressant medication for the rest of their lives. This response is controlled by the T-lymphocytes.

Our immune system is beautifully tuned to protect us from the microorganisms around us and it is constantly improving.

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Practise This Question

Which of the following is/are (an) example(s) of passive immunity?