Immunity is defined as the ability of the body to protect against all the pathogens or the foreign bodies like bacteria, virus, and other toxic substances, invading into the body. It acts as the defense mechanism of our body. The lack of immunity is known as susceptibility.
The branch of biology which mainly deals with the study of immunity, immune systems and allergy is called immunology. There are two major types of immunity:
- Innate immunity or natural or nonspecific immunity.
- Acquired immunity or adaptive immunity.
Let explore more about the Acquired immunity.
What is Acquired Immunity?
An ability of the immune system to adapt itself to disease and to generate pathogen-specific immunity is termed as acquired immunity. It is also known as adaptive immunity.
An individual acquires the immunity after the birth, hence is called as the acquired immunity. It is specific and mediated by antibodies or lymphocytes which make the antigen harmless.
The main function of acquired immunity is to relieve the victim of the infectious disease and also prevents its further attack in future. It mainly consists of an advanced lymphatic defense system which functions by recognizing the own body cells and not reacting to them.
In this immune system, our body identifies the pathogens which have encountered in the past. It is mainly caused when a person comes in contact with the pathogen or its antigen.
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 microbes 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
Acquired immunity comprises two special cells:
- 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.
Types of Acquired Immune Response
- Humoral Immune Response:
The antibodies produced by B-lymphocytes are present in the blood cells and they are transported all over the body. This is why it is called the humoral immune response as it consists of an antibody 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 any of our sense organs stops functioning, it can be transplanted to replace the malfunctioning organs. 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 foreign bodies. 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, because our body might reject the transplanted organ. 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 immunosuppressant medication for the rest of their lives. This response is controlled by the T-lymphocytes.
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