antigen

noun

: any substance (such as an immunogen or a hapten) foreign to the body that evokes an immune response either alone or after forming a complex with a larger molecule (such as a protein) and that is capable of binding with a product (such as an antibody or T cell) of the immune response

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An antibody is a protein produced by your immune system to fight outside invaders. Since the enemy substance actually triggers the production of antibodies, such substances are called antigens—anti- being short for antibody, and -gen meaning "producer". (In a similar way, an allergen produces an allergy, and a pathogen produces a pathology or disease.) Antigens are often rodlike structures that stick out from the surface of an invading organism—usually a bacterium or a virus—and allow it to attach itself to cells in the invaded body. But unfortunately for them, in doing so they let the immune system know they're present, and the body is flooded with an army of Pac-Man-like antibodies.

Examples of antigen in a Sentence

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These antigen tests, often called rapid tests, detect proteins called antigens from the virus that causes Covid-19. Sam Tupper, CNN, 30 Oct. 2024 Understanding how the immune system responds to this understudied antigen could improve diagnosis and treatment. Trirupa Chakraborty, Discover Magazine, 25 Oct. 2024 The Food and Drug Administration, however, has said those expiration dates are subject to change, providing a list of the tests that have had their dates extended. COVID-19 rapid antigen tests allow people to check for SARS-CoV-2 infections without help from professionals. Tribune News Service, The Mercury News, 13 Nov. 2024 Greywolf Therapeutics, an antigen modulation technology developer, Darlene Deptula-Hicks as CFO. Ellie Austin, Fortune, 20 Nov. 2024 See all Example Sentences for antigen 

Word History

Etymology

German, from French antigène, from anticorps antibody + -gène -gen

First Known Use

1908, in the meaning defined above

Time Traveler
The first known use of antigen was in 1908

Dictionary Entries Near antigen

Cite this Entry

“Antigen.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/antigen. Accessed 30 Dec. 2024.

Kids Definition

antigen

noun
: a substance (as a protein) that causes the body to form antibodies against it when it is introduced into the body either alone or as part of a microscopic plant or animal

Medical Definition

antigen

noun
: any substance (as an immunogen or a hapten) foreign to the body that evokes an immune response either alone or after forming a complex with a larger molecule (as a protein) and that is capable of binding with a product (as an antibody or T cell) of the immune response

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