antigen

noun

an·​ti·​gen ˈan-ti-jən 

-ˌjen

: 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

antigenic

ˌan-ti-ˈje-nik 

adjective

antigenically

ˌan-ti-ˈje-ni-k(ə-)lē 

adverb

antigenicity

ˌan-ti-jə-ˈni-sə-tē 

noun

Did you know?

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

Recent Examples on the Web

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

Hugh Mason, an associate professor at Arizona State University who has been studying the use of plants for the production of vaccine antigens for more than 30 years, said there are significant technical hurdles to delivering a precise amount of a vaccine in a piece of fruit or a vegetable. —Nate Trela, USA TODAY, 26 Sep. 2024

AstraZeneca later redesigned the antigens in the vaccine, earning back the CDC's recommendation starting in 2018. —Alexander Tin, CBS News, 20 Sep. 2024

Word History

Etymology

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

First Known Use

1908, in the meaning defined above

Phrases Containing antigen

• antigen-presenting cell
• carcinoembryonic antigen
• human leukocyte antigen
• prostate-specific antigen

Kids Definition

antigen

noun

an·​ti·​gen ˈant-i-jən 

-ˌjen

: 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

antigenic

ˌant-i-ˈjen-ik 

adjective

Medical Definition

antigen

noun

an·​ti·​gen ˈant-i-jən 

: 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

antigenic

ˌant-i-ˈjen-ik 

adjective

antigenically

-i-k(ə-)lē 

adverb