: 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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In biology, when the immune system attacks the body's own tissues, the result is autoimmune disease. Abhik Biswas, Forbes.com, 2 July 2026 Basye's son and husband both have celiac disease, which is an autoimmune disease that causes severe digestive issues, joint pain and headaches when encountering gluten. Lexi Lane, PEOPLE, 22 June 2026 Researchers believe there's incredible potential in this approach to treating chronic infections, autoimmune disease and cancer, while also providing a novel therapy to prolong our health in older age. New Atlas, 2 July 2026 His blood work was generally normal except for elevated IgE, a signal of immune responses linked to allergies, autoimmune disease, and parasitic infections. Beth Mole, ArsTechnica, 26 June 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 Jul. 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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