: of, relating to, or caused by autoantibodies or T cells that attack molecules, cells, or tissues of the organism producing them
autoimmune diseases

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Any healthy body produces a variety of antibodies, proteins in the blood whose job is to protect the body from unwanted bacteria, viruses, and cancer cells. The cells and organs that deal with such infections make up the immune system. In some people and animals, for various reasons, the antibodies become overactive and turn on the body's healthy tissues as well; the result is an autoimmune disease—an immune response directed against one's own self. More than eighty autoimmune diseases have been identified, the best-known being type 1 diabetes, multiple sclerosis, lupus, and rheumatoid arthritis.

Examples of autoimmune in a Sentence

Recent Examples on the Web
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Additionally, Frankel was diagnosed with long COVID and the autoimmune disorder POTS in 2023. Vanessa Etienne, PEOPLE, 4 Aug. 2026 The company is separately facing safety questions over its drug Tavneos, which is intended to treat a rare autoimmune condition. Bloomberg, Mercury News, 3 Aug. 2026 Chronic stress has implications for general health too, and can cause inflammatory and autoimmune symptoms. Erin Clabough, The Conversation, 31 July 2026 Some can change overnight — asthma exacerbated by poor air quality, like during wildfires, or autoimmune conditions that flare on hot days. Isabella Cueto, STAT, 30 July 2026 See All Example Sentences for autoimmune

Word History

Etymology

auto- + immune, after autoimmunity, borrowed from French auto-immunité

First Known Use

1952, in the meaning defined above

Time Traveler
The first known use of autoimmune was in 1952

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Cite this Entry

“Autoimmune.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/autoimmune. Accessed 8 Aug. 2026.

Kids Definition

autoimmune

adjective
: relating to or caused by an abnormal condition in which an organism's immune system attacks and destroys parts of its own cells or tissues
multiple sclerosis is an autoimmune disease

Medical Definition

autoimmune

adjective
: of, relating to, or caused by antibodies or T cells that attack molecules, cells, or tissues of the organism producing them
autoimmune diseases
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