What is an Antigen?

What is an Antigen?

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By Dr. Sanchari Sinha Dutta, Ph.D.Reviewed by Emily Henderson, B.Sc.

Any substance that induces the immune system to produce antibodies against it is called an antigen. Any foreign invaders, such as pathogens (bacteria and viruses), chemicals, toxins, and pollens, can be antigens. Under pathological conditions, normal cellular proteins can become self-antigens.