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Name: Andrew
Status: Student
Age: N/A
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Date: February 2003

What is the difference between antigen and antibody?

An antibody is a protein produced by a host to bind to, and thus inactivate, foreign particles. The particle is called the antigen. It is frequently but not always a protein. The binding of antibody to antigen is very specific, so that, if all goes well, the antibody binds to that specific antigen only. The part of the antigen molecule to which the antibody binds is called the epitope.

You can read more about antibodies and the immune system in humans in a display on 'how we fight bacteria' in the Virtual Museum of Bacteria,

You'll find useful other web resources in there.

Trudy Wassenaar
Curator of the Virtual Museum of Bacteria

Antigens are anything that can stimulate an immune response in your body. They are usually described as anything that your body recognizes as foreign, or not belonging to you. In one part of the immune response, the B cells manufacture antibodies to fight off the antigens. They are produced by your B cells and are shaped in such a way that they are able to attach to antigens and remove them from the body.


An antibody is a protein that is secreted by an immune cell in response to a stimulus. The actual thing that binds to a receptor on the immune cell and stimulates it is called the antigen (as in ANTIbody GENerator).

Paul Mahoney, PhD

An antigen is anything that is recognized by the body's immune system as foreign. An antibody is the protein that is produced against a specific antigen.

Peter Faletra

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