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Difference Between Antigen and Antibody

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In immunology, Antigen and Antibody are two interrelated terms. The primary distinction between antigen and antibody is that an antigen is a substance that may trigger an immune response in the body, whereas an antibody is a globin protein that is produced in reaction to a specific antigen. An antigen must bind to an antibody or T-cell receptor in order to generate an immune response.

What is Antigen?

Antigens also known as immunogens are substances or toxins in your blood which stimulate your immune system to fight them. Antigens are typically bacteria or viruses but they can also be foreign substances that endanger your health. This type of battle is known as an immunological response.

The presence of antigens activates your body’s disease-fighting white blood cells, known as lymphocytes. Due to the presence of antigens white blood cells produce antibodies that fight against the antigens.

For example: when a common cold virus enters the body, it induces the body to produce antibodies in order to prevent illness.

What is Antibody?

Immunoglobulin (Ig) is another name for antibody (Ab). Plasma cells produce these large Y-shaped blood proteins. They bind to foreign particles and infiltrate them. Antigens are foreign pathogens that enter the body and have the ability to elicit a response from our immune system, either by grouping together with a larger molecule or by binding with antibodies for a specific immune reaction. As a result, antigens stimulate the system’s ability to generate antibodies. 

Antibodies can be found in both the bloodstream and the lymphatic system. The binding of antibodies to their particular antigens neutralizes the antigen and initiates an immunological response. This binding can immobilize infections in circulation.  It also leads to complement reactions which lyse the pathogen. 

Difference Between Antigen and Antibody

Antigen 

Antibody

An antigen is an outside substance that stimulates the formation of antibodies by inducing an immune response. An antibody is a glycoprotein that is formed in reaction to and in response to a specific antigen.
They are also known as immunogens since they act against the immune system. As they are immune system globulin proteins, they are also known as immunoglobulins. 
It is responsible for illnesses and allergic reactions.   It safeguards the immune system by lysis, phagocytosis, and precipitation of an antigenic substance.
Proteins and carbohydrates are the most common however lipids and nucleic acids can also act as antigens when combined with proteins or carbs. They are merely proteins.
They include specialized areas known as epitopes that interact with antibodies. They have specialised areas known as paratopes that interact with antigen epitopes.
It originates from outside the body. It originates within the body .
Endogenous, exogenous, and autoantigens are types of Antigen  IgG, IgM, IgA, IgD and IgE types of antibody
It is denoted by Ag  It is denoted Ab

Similarity Between Antigen and Antibody

  • Antigens and antibodies both have roles in triggering an immunological response.
  • Antigens and antibodies are both engaged in the destruction of foreign substance. 

Conclusion

Antigens and antibodies are both substances that are involved in the body’s immunological processes. An antigen is a substance that can cause the body’s immune system to react. The globin protein produced in response to a specific antigen is known as an antibody. The primary distinction between antigen and antibody is the function of every substance in the immune system.

FAQs on Antigen and Antibody

Question 1: What are antigens’ properties?

Answer : Antigens have the following properties:

  1. In order to induce an immune reaction, the antigen should be a distant substance.
  2. The antigens have molecular mass ranging from 14,000 to 6,00,000 Da.
  3. They mostly consist of proteins and carbohydrates.
  4. The greater their chemical complexity, the more immunogenic they will be.

Question 2: Are antigens and antibodies the same thing?

Answer : Antigens enable your body to build a defence against potential invaders. Once generated, antibodies circulate throughout your body to recognise, attack, and eliminate the same sort of antigens if they re-enter the body.

Question 3: How do antigens and antibodies collaborate?

Answer : Antibodies bind to a specific antigen and make it easier for immune cells to eliminate the antigen. T cells target antigens directly and help in immune response control. They also produce chemicals called cytokines, which control the overall immune response.

Question 4: What is the antigen and antibody principle?

Answer : An antigen is any substance that, when administered parenterally to an animal, induces the formation of antibodies. The antibody produced can be found in serum or other bodily fluids and should react with the antigen used to induce its formation.

Question 5: What is an antibody’s size?

Answer : Antibodies are heavy (150 kDa) proteins that are around 10 nm in size and are arranged in three globular sections that form a Y shape.


Last Updated : 02 May, 2023
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