Antigens are large molecules (usually proteins) on the surface of cells, viruses, fungi, bacteria, and some non-living substances, such as toxins, chemicals, drugs, and foreign particles. The immune system recognizes antigens as being foreign to the body and produces antibodies that destroy substances containing antigens.
Reviewed last on: 5/31/2009
Mark James Borigini, Associate Clinical Professor of Medicine, University of California, Irvine, Irvine, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.