Antibody
An antibody is a protein produced by the body's immune system when it detects harmful substances, called antigens. Examples of antigens include microorganisms (bacteria, fungi, parasites, and viruses) and chemicals.
Antibodies may be produced when the immune system mistakenly considers healthy tissue a harmful substance. This is called an autoimmune disorder.
Each type of antibody is unique and defends the body against one specific type of antigen.
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 and produces antibodies that destroy substances containing antigens.
References
Abbas AK, Lichtman AH, Pillai S. Antibodies and antigens. In: Abbas AK, Lichtman AH, Pillai S, eds. Cellular and Molecular Immunology. 10th ed. Philadelphia, PA: Elsevier; 2022:chap 5.
Version Info
Last reviewed on: 7/23/2024
Reviewed by: Linda J. Vorvick, MD, Clinical Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
