Science glossary film: Antigen

A molecule, or fragment of a molecule, that triggers an immune response, causing the body to produce specific antibodies against it. Antigens are usually molecules present on the surface of bacteria, viruses or other microorganisms. There are also some nonmicrobial antigens, such as pollen, which can trigger an immune response in some cases.

Antigens are usually molecules present on the surface of bacteria, viruses or other microorganisms. There are also some nonmicrobial antigens, such as pollen, which can trigger an immune response in some cases.