- A substance that is capable of causing the production of antibodies or a T-cell response in the body, especially a protein or polysaccharide that is present on the surface of microorganisms, cancer cells, or other foreign substances, and is recognized as foreign by the immune system.
- Any substance that can cause an immune response.
Early 20th century: from anti- + -gen.
- The flu virus is an antigen that triggers an immune response.
- The antigen test is used to detect the presence of a specific substance in the blood.
- The vaccine is designed to train the immune system to recognize and attack a specific antigen.
- The antigen-presenting cells are responsible for displaying antigens to the immune cells.
- The antigenicity of a molecule refers to its ability to stimulate an immune response.