Immune Response

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The immune system

The immune system protects the body from potentially harmful substances by recognizing and responding to so-called antigens. Antigens are large molecules (usually proteins) on the surface of cells, viruses, fungi, or bacteria. Some non-living substances such as toxins, chemicals, drugs, and foreign particles (such as a splinter) can be antigens. Substances that contain these antigens are recognized and destroyed by the immune system . Even your own body cells have proteins that are antigens (these include a group of antigens called HLA antigens). Your immune system learns to see these antigens as "normal" and does not usually react against them.

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