Antigen A molecule or molecular structure that is recognized by the immune system, specifically by antibodies, B cells, or T cells, is frequently a protein or polysaccharide. These molecules are primarily responsible for inducing an immune response that results in the development of antibodies that have the specific ability to bind to them. The molecule may be neutralized by this binding or marked for eradication by other immune cells.
Table of Contents
Definition
“A molecule known as an antigen is what starts the production of an antibody and triggers an immune response.”

Properties
The properties are as follows
- For an it have to trigger an immune response, it must be an alien material.
- The molecular mass of them ranges from 14,000 to 6,00,000 Da.
- They mostly consist of carbohydrates and proteins.
- They will be more immunogenic the more chemically complicated they are.
- It Have differ across species.
- The immunogenicity is influenced by age. Individuals that are really young or elderly have very low immunogenicity.
Types
1) On the basis of Origin
a) Exogenous
External substances that enter the body by injection, inhalation, or other means are known as exogenous substances. These are the most prevalent kind and include food allergens, pollen, aerosols, etc.

b) Endogenous
The body produces endogenous antigens as a result of cellular metabolism, bacterial or viral infections, or both.
c) Autoantigens
Autoantigens are “self” proteins or nucleic acids that, as a result of genetic or environmental changes, are targeted by the immune system and subsequently cause autoimmune disorders.
d) Tumour Antigens
MHC-I and MHC-II are examples substances found on the surface of tumor cells that trigger an immunological response in the host. Many tumors evolve a defense mechanism to elude the body’s immune system.
e) Native
Native it have not yet been processed by an antigen-presenting cell.
2) On the Basis of Immune Response
a) Immunogen
These can trigger an immunological response on their own and can be proteins or polysaccharides.
b) Hapten
These are alien, non-protein compounds that need a carrier molecule in order to trigger an immunological reaction.
Structure
The parts of the antigen are called epitopes. Each one consists of many epitopes. A minimum of two binding sites on an antibody allow it to attach to certain epitopes.
The lock and key mechanism governs how they and antibody join.
Immunity is the body’s capacity to respond to them and disease-causing substances through the immune system. This immunity can be obtained by immunizations or is inborn.
Examples
Pollen, bacteria, parasitic worms, and viruses.
Frequently Asked Question
1. What is the structure and properties of ?
For an antigen to trigger an immune response, it must be an alien material. The molecular mass of them ranges from 14,000 to 6,00,000 Da. They mostly consist of carbohydrates and proteins. They will be more immunogenic the more chemically complicated they are.
2. What is an example of an antigen?
“Toxins, chemicals, germs, viruses, and other materials originating from outside the body are examples. They on body tissues and cells, including cancer cells, can trigger an immune response.”
3. What are the different types of antigen cells?
“In peripheral lymphoid organs, dendritic cells, macrophages, and B cells are the three primary kinds of cells that have the ability to activate T lymphocytes.”
4. What is the structure of an antibody and antigen?
Every antibody molecule is almost the same as the B cell’s antigen receptor from which it was formed. These proteins’ fundamental structure is made up of two pairs of flexible Y-shaped polypeptide chains, which are extended sequences of amino acids joined by peptide bonds.
What is an antigen and a pathogen?
It is a substance that triggers the production of antibodies. Pathogens are harmful microorganisms that can cause diseases in their host.
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