What is the difference between Antigen and Antibody?

For someone who knows about the terms, it's like asking the difference between a hero & a villain. During the COVID-19 pandemic, these two terms were constantly bombarded throughout the media. The consequence has caused complete confusion about the meaning of the terms. The article aims to clear the jargon & educate the difference between antigens & antibodies. Overall, the closest comparison to the pair of antigen & antibody is the Yin & Yang. Let’s understand them in detail.

The difference between Antigen and Antibody - The Basics

Antigens & antibodies both play a vital role in our body. They are interdependent. While antigens try to destroy our immune system & cause the deterioration of our health, antibodies are the protectors of our immune system & fight the antigens to keep us healthy & fit. Antigens are there to weaken you, while antibodies protect you from the antigens.

Will PPE stay in our lives? Check out our blog on the future of PPE.

What is an antigen?

An antigen (also known as an immunogen) is any substance, particle, toxin, or organism which isn’t recognized by the human body. It causes the triggering of the body’s immune system. Based on the type of origin (entry in the body) they are classified into two types. The endogenous antigens are the ones that are produced within the body, while the exogenous antigens are the ones that enter the body from external sources. Autoantigens, or self-antigens, are made by your body to fight your cells and are usually an illness sign such as an autoimmune condition.

Did you know?

There are unique antigens that cause autoimmune diseases. These antigens are called autoantigens. Also, some antigens are produced by the tumor cells in the body. These antigens are called tumor antigens. These antigens are made by one’s body to fight its cells. They cause autoimmune diseases like Rheumatoid Arthritis, Lupus, and others.

Curious ones can check out more details on autoimmune diseases.

What is an antibody?

Antibodies (alternatively known as immunoglobins) are unique proteins synthesized by immune (White Blood lymphocytes) cells. They are produced by the immune cells in response to the antigens. The major types of antibodies are as follows -

1. IgA - They remove the antigens from the body through body fluids like mucus.
2. IgD - They adhere to B lymphocytes & help in releasing IgM.
3. IgE - They are produced in response to allergens.
4. IgM - Upon stimulus from IgD, they attack the antigens.
5. IgG - The most common type of antibody, which help in detoxifying the body.

Curious ones can check out our blog on PPE for phlebotomists.

Did you know?

Immune cells can detect the presence of antigens. It is possible because of memory B cells. They serve the immune system by helping it recognize the antigen & facilitate the appropriate synthesis of antibodies. It allows quick & effective responses against the antigens.

How do antibodies eliminate antigens?

Antigens have a specific surface called an epitope. Similarly, an antibody that can neutralize the antigens has a complimenting surface called a paratope. The antibody’s paratope fits into the antigen’s epitope just like a key fits into a lock. In some cases, it is further facilitated for other antibodies to destroy the antigen. Due to this, there are specific antibodies that can destroy specific antigens (just like a specific key can open a particular lock).

What are vaccines? Does the difference between antigen & antibody affect it?

The vaccine contains antigens in its dormant form. Remember the memory B cells? The vaccine helps in activating the memory B cells, which remember the antigen & help the immune system produce appropriate antibodies. It is like a lioness teaching hunting to its cubs by exposing weakened prey to them. So, vaccines are weakened antigens that help in training the body to produce appropriate antibodies. Some vaccines contain genetic material of antigens which help in triggering antibody synthesis.

What is the difference between antigen & antibody tests?

An antigen test helps in the identification of whether the body is under an antigen infestation or not. When a person is ill, an antigen test can help in identifying the antigen plaguing the body. A healthy body may produce a negative result for specific antigens. These tests have lower accuracy than PCR tests. Though, the positive aspects are relatively rapid results & cheaper costs.

An antibody test helps in the identification of whether the body has produced the antibodies or not. The human body takes time to produce antibodies. So, a negative result may not always mean that the body isn’t producing antibodies. A positive outcome indicates that the body’s immune system has kicked in, and the antibodies have started to act on the antigens.

FAQ: What are monoclonal therapeutic antibodies?

Monoclonal antibodies are lab-synthesized antibody clones that are meant to function just like the antibodies made by the human body. Monoclonal antibodies are used for immunotherapy which is why they are also called therapeutic antibodies. US FDA has approved 100+ therapeutic antibodies. Many experts claim that therapeutic antibodies can cure a plethora of autoimmune diseases, cancers, and viral diseases (even COVID-19 & Zika).

Therapeutic antibodies are highly specialized antibodies that have greater specificity for targeted antigens. They perform three tasks - 

1) Neutralize the antigen 

2) Trigger an immune signal & consecutively an immune reaction

3) Inviting killer T cells which eliminate the antigen.

Curious ones can check out more on monoclonal antibody therapy.

Did you know?

In 1984, the scientist duo George Köhler & Cesar Milstein won the Nobel Prize in physiology for their work on the infinite production of monoclonal antibodies.

Conclusion

Antigens & antibodies are completely opposite entities. Antigens are entities that can cause harm to the body and thus activate the immune system to synthesize immunoglobins or antibodies. These antibodies are antigen-specific and destroy its counterpart by following the lock & key pattern. The immune system is capable of retaining memory of the antigens, thus helping the body to take swift & effective action the next time the same antigen attacks the body. These distinct characteristics & their interdependence of antigens & antibodies are exploited for vaccine manufacturing. Moreover, they are also used for tests to identify if a person is prone to a disease or has recovered from it.