Definition: An antigen is a chemical substance, usually on the surface of a foreign microscopic object such as bacteria, virus or cancer cell.
Cells called lymphocytes, which are part of your immune system, recognize this chemical as being foreign to your body. They then produce antibodies that attack that specific antigen. Cancer cells are abnormal and do produce some partly foreign-looking antigens on their surface. However, in addition to appearing only partly foreign to your immune system, once a cancer has been found it is composed of at least millions of cells. At this point your immune system is basically overwhelmed.
Pronunciation: AN-tih-jen
Common Misspellings: antegen anygen
Examples:
Research is underway to find antigens on ovarian cancer cell surfaces that can be attacked by antibodies.
