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Antibodies are special proteins that help your body fight off harmful things like germs, toxins, and allergens. They work by sticking to these bad things and signalling to your immune system to attack and destroy them. Think of them like little soldiers that protect your body from getting sick.

How are antibodies produced?

Antibodies are made by a type of white blood cell called B cells. There are a lot of different B cells in our body, and each one creates a specific type of antibody. These antibodies are all identical and are called monoclonal antibodies. It's like having an army of soldiers that are all trained to fight one specific enemy. Pretty amazing, right?

The structure of an antibody

Antibodies are special proteins that have a unique shape made up of four chains. Two of these chains are longer and are called heavy chains, while the other two are shorter and are called light chains. These proteins are also called globular glycoproteins because they are round and have sugars attached to them.

The amazing thing about antibodies is that they have a part that stays the same and a part that changes depending on what they need to fight. The part that changes is called the variable region, and it's the part that binds to the specific bad thing (antigen) that needs to be destroyed. The constant region, on the other hand, stays the same and helps the antibody attach to cells like B cells.

The part of the antibody that actually binds to the antigen is called the antigen-binding site, and it's found at the end of the variable region. Finally, the four chains are held together by disulfide bridges, kind of like a super-strong glue.

Structure of an antibody
Structure of an antibody

The importance of antibody structure

The structure of an antibody is crucial to its function, and the most critical part is the antigen-binding site. This site has a unique and highly specific 3-D structure that enables it to attach only to complementary antigens. Because antibodies are made of proteins, they can create very specific shapes that allow them to bind exclusively to particular antigens. This specificity is what makes antibodies so remarkable, they can be designed to target particular cells and pathogens with great precision, providing a powerful and adaptable defense against a wide range of threats.

Specific antigens binding to their complementary sites on the antibody
Specific antigens binding to their complementary sites on the antibody

The characteristic 'Y' shape is also important. As you will see later, the structure of two binding sites instead of one allows antibodies to bind to two different antigens at once. This is important because it allows antibodies to effectively 'clump' together pathogens and other particles.

The antigen-antibody complex

Antibodies bind to antigens via the specific binding sites found on the ends of the variable region. Each binding site is made up of a sequence of amino acids that form a specific 3-D shape. This shape is complementary to a specific antigen. When an antibody and antigen bind together they form what is known as an antigen-antibody complex.

The antigen-antibody complex
The antigen-antibody complex

How do antibodies work?

Antibodies work indirectly by preparing the antigens for destruction by phagocytes, which are specialized white blood cells that engulf and digest the pathogens. The primary role of antibodies is to tag the antigens, making it easier for the immune system to recognize and destroy them.

There are two primary ways that antibodies do this:

  1. Opsonization: Antibodies attach to the surface of the antigen, making it more recognizable to phagocytes. This process is known as opsonization, and it makes it easier for the phagocytes to engulf and destroy the antigen.
  2. Complement activation: Antibodies can also activate the complement system, which is a group of proteins that work together to destroy pathogens. When antibodies bind to the antigen, they trigger the complement system, which causes a series of chemical reactions leading to the destruction of the pathogen.

Overall, antibodies play a key role in the immune system by tagging antigens for destruction and helping to activate the body's defenses.


I apologize for the mistake earlier. You are correct that agglutination is another method that antibodies use to fight against pathogens.

Agglutination occurs when antibodies bind to multiple antigens, causing them to clump together. This process is especially useful when dealing with pathogens that have multiple antigens on their surface. By clumping these antigens together, antibodies can make it easier for phagocytes to engulf and destroy the pathogens.

Antibodies have two binding sites, which means they can bind to two different pathogens or two different antigens on the same pathogen at the same time. This allows them to create larger clumps of pathogens, making it easier for the immune system to recognize and destroy them.

Overall, agglutination is an important mechanism that antibodies use to fight against pathogens, and it highlights the remarkable specificity and adaptability of the immune system.

The agglutination of antigens
The agglutination of antigens


Following agglutination, antibodies can act as chemical markers that stimulate phagocytes to move towards the clump of antibodies and antigens. Phagocytes can then engulf the clump of pathogens and destroy them in phagocytosis.

Antibodies and toxins

Just to reiterate, antibodies are a vital component of the immune system that help to identify and neutralize pathogens and cancerous cells. They work by binding to complementary antigens on the surface of these cells and forming an antigen-antibody complex. Antibodies have a quaternary structure made up of four chains, including two heavy chains and two light chains. The variable region at the end of each chain is specific to each type of antibody and includes the antigen-binding site. Monoclonal antibodies are a specific type of antibody that can be cloned to produce large quantities of identical antibodies, which can be used in a range of scientific and medical applications, including cancer treatment and disease diagnosis.


What is an antibody?

An antibody is a specific type of protein produced by B cells and plasma cells in the humoral immune response. Antibodies bind to specific foreign antigens to prepare them for destruction via phagocytosis.

What do antibodies do in blood?

Antibodies bind to specific foreign antigens. Because antibodies have two binding sites, they can bind to multiple antigens at once, causing agglutination (clumping together) of cells and particles. Antibodies also bind to some toxins produced by pathogens, neutralizing them so that they cannot cause harm to the body's cells.

What can cause antibodies?

 Antibodies are produced in response to the presence of non-self antigens being detected by T lymphocytes in the body. This may be caused by infection with a virus or bacteria, or the inhalation of pollen, for example.

What is the difference between monoclonal and polyclonal antibodies?

Monoclonal antibodies are produced by a singular B cell so that each antibody is identical, while polyclonal antibodies are produced by several different immune cells, and are not all identical.

How are monoclonal antibodies produced?

 Monoclonal antibodies are produced by B cells. They can be manufactured for medical use using mice. In this method, mice are exposed to the non-self material against which an antibody is required, causing the mouses' B cells to produce antibodies. These B cells are then fused with cancer cells so that they divide rapidly, forming what is known as hybridoma cells, from which antibodies can be extracted.

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