autoimmune

adjective

au·​to·​im·​mune ˌȯ-tō-im-ˈyün 

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

autoimmune diseases

autoimmunity

ˌȯ-tō-im-ˈyü-nə-tē 

noun

autoimmunization

ˌȯ-tō-ˌim-yə-nə-ˈzā-shən 

also -im-ˌyü-

noun

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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

Lupus is a chronic autoimmune disease that occurs when the immune system, which is designed to protect the body from infection and disease, attacks its own tissues, per the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). —Korin Miller, Flow Space, 6 Jan. 2026

Her partner Julie Divola informed The New York Times that Smith had died following struggles with long-term symptoms from a rare autoimmune disease over the last decade. —Brendan Le, PEOPLE, 5 Jan. 2026

As a result, autoimmune diseases can quietly hide in plain sight. —Daryl Austin, USA Today, 5 Jan. 2026

Studies found equal or lower rates of autoimmune disorders among vaccinated children. —Jody Mamone, Hartford Courant, 2 Jan. 2026

Word History

Etymology

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

First Known Use

1952, in the meaning defined above

Kids Definition

autoimmune

adjective

au·​to·​im·​mune ˌȯt-ō-im-ˈyün 

: 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

au·​to·​im·​mune -im-ˈyün 

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

autoimmune diseases