main menu   -   articles   -   prostate   -   stories   -   sexuality   -   resources   -   glossary   -   search     From Phoenix5's Prostate Cancer Glossary antigen Definition: (AN-tee-jen) Any substance that stimulates the immune system. Antigens are often foreign substances such as bacteria or viruses that invade the body. The role of the prostate-specific antigen (PSA) is not fully understood. Some speculate that it might be the body's way to fight tumors but more research is needed. make another selection #s   A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  WXYZ main menu   -   articles   -   prostate   -   stories   -   sexuality   -   resources   -   glossary   -   search The Glossary Booklet   -   The Personal Edition Definitions are provided for education only and are not medical advice. Created exclusively for Phoenix5. © 2002 Phoenix5.