Home » + English • Glossary » Antigen Antigen By Andres Trevino September 21, 2004 + English Glossary No comments Tweet Pin It Any substance that stimulates the immune system to produce antibodies. Antigens are often foreign substances such as invading bacteria or viruses. More definitions via Google here. More via Wikipedia here. Related Posts Dr. Derek Callaway visits Andy’s room Top ten reasons why NOT to preserve your baby’... Healing