Last modified on July 15, 2012, at 02:05

Antigen

An antigen is any foreign or unrecognised substance that is capable of inducing an immune response, usually involving the production of antibodies which bind to, and disable, the antigen. Antigen may be a protein, protein fragment, or even metallic particles (for example, due to wearing of a metallic hip replacement). When an antigen is injected into the bloodstream, as through vaccination, it causes the body to produce antibodies.