Antigens are foreign substances (e.g. [[bacteria]] or [[viruses]]) in the body that are capable of causing disease. The presence of antigens in the body triggers an immune response, usually the production of [[antibodies]]. | Antigens are foreign substances (e.g. [[bacteria]] or [[viruses]]) in the body that are capable of causing disease. The presence of antigens in the body triggers an immune response, usually the production of [[antibodies]]. |