What does autoimmunity mean?
Autoimmunity is the condition in which the body's immune system — normally responsible for defending against infections — mistakenly identifies its own healthy cells, tissues, or organs as foreign and attacks them. This loss of self-tolerance underlies a broad class of illnesses known as autoimmune diseases, including type 1 diabetes, rheumatoid arthritis, multiple sclerosis, and lupus. The word is most often encountered in medical, scientific, and health-reporting contexts rather than casual speech, and it functions as an uncountable noun: one might speak of 'a breakdown of tolerance leading to autoimmunity' or of 'the role of autoimmunity in chronic disease.' Its connotations are clinical and serious, since it names a category of often lifelong conditions. Closely related is the adjective 'autoimmune,' which is considerably more common in everyday usage, as in 'autoimmune disorder' or 'autoimmune response.' Understanding autoimmunity matters because it reframes many chronic illnesses not as failures of defense but as cases of defense gone awry — the immune system working too well, but against the wrong target. Researchers continue to investigate why autoimmunity develops and why it disproportionately affects certain groups.
nounThe condition in which the body's immune system mistakenly attacks its own healthy cells and tissues. It also refers more broadly to the immunological state or mechanism underlying such self-directed immune responses.
- The physiological condition or process in which the immune system produces a response against the body's own cells and tissues, causing disease.
- The general phenomenon or property of immune self-reactivity studied in immunology.
"Autoimmunity is now recognized as a contributing factor in a wide range of chronic diseases, from type 1 diabetes to lupus."
"Researchers are studying why women are disproportionately affected by autoimmunity."
"A breakdown in tolerance can lead to autoimmunity, in which T cells attack the body's own tissues."
Very rare. Autoimmunity is almost always used as an uncountable noun; a plural would appear only in highly specialized writing distinguishing distinct types or instances of autoimmune response, where phrasing such as 'forms of autoimmunity' is more typical.
"The review catalogued distinct autoimmunities affecting endocrine, neurological, and gastrointestinal tissues."
Your immune system's entire job is to defend you — but in over 80 different autoimmune conditions, it turns its weapons on you instead.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of autoimmunity
The word autoimmunity combines the Greek prefix 'auto-', meaning 'self', with 'immunity', from Latin 'immunitas', meaning freedom or exemption (originally from public service or burdens), derived from 'immunis'. The concept emerged in the early twentieth century as scientists such as Paul Ehrlich explored whether the immune system could turn against the body itself, a notion he called 'horror autotoxicus'. The adjective 'autoimmune' became established in medical vocabulary around the mid-twentieth century, with 'autoimmunity' developing as its corresponding noun to name the underlying condition and field of study.
Related word forms
How autoimmunity is actually used
Autoimmunity is a formal, technical term used primarily in medical, scientific, and health-journalism contexts; it is uncommon in everyday conversation. It is typically uncountable when referring to the condition in general, though it occasionally appears with modifiers (e.g., 'a form of autoimmunity'). The related adjective 'autoimmune' is far more common in phrases like 'autoimmune disease'.
Easily confused with autoimmunity
Autoimmune is an adjective describing diseases or responses involving the immune system attacking the body, while autoimmunity is the noun naming that condition or process itself.
Immunity refers to protection against disease, whereas autoimmunity refers to the immune system's harmful misdirected action against the body it should protect.