Glossary Term:






a foreign substance that causes the body’s immune system to respond by making antibodies. For example, the immune system responds to antigens that are part of bacteria and viruses to help people resist infections. Certain cancer cells have antigens that can be found by lab tests. They can help in diagnosing those cancers and in watching response to treatment. Other cancer cell antigens play a role in immune reactions that may help the body resist cancer. See also antibody, immune system.