What is an antinuclear antibody?

An antibody is a protein made by white blood cells (B cells). Antibodies help defend against invaders (for example, viruses and bacteria) that cause disease or infection in the body. When antibodies make a mistake by recognizing our “self” cells as being “foreign,” they are called autoantibodies.

Most of us have autoantibodies, but usually a very small amount. If there are enough autoantibodies present, a cascade of inflammation (swelling) is started. This causes our immune system to attack our own body (autoimmune disease).

An antinuclear antibody (ANA) is an autoantibody that mistakenly binds to normal protein within the nucleus of a cell. ANAs are usually found in people who have autoimmune conditions such as systemic lupus erythematosus. They may also be seen in other autoimmune diseases, such as mixed connective tissue disease, Sjogren's syndrome, dermatomyositis, polymyositis and scleroderma.

However, not everybody who has ANAs has an autoimmune disease. For instance, ANAs could be found in 10-15 percent of completely healthy children. They could be briefly present in the setting of intercurrent infection (an infection that occurs while the person already has another infection) or in people who are taking certain drugs (for example, hydralazine, isoniazid, procainamide, and some anticonvulsants).

Last reviewed by a Cleveland Clinic medical professional on 01/18/2018.


  • American College of Rheumatology. Antinuclear Antibodies (ANA). Accessed 2/11/2019.
  • Malleson NP, Mackinnon MJ, Sailer-Hoeck, et. al. Review for the generalist: The antinuclear antibody test in children - When to use it and what to do with a positive titer. Pediatr Rheumatol Online J. 2010; 8: 27. doi: 10.1186/1546-0096-8-27
  • American Association for Clinical Chemistry/Lab Tests Online. Antinuclear Antibody (ANA). Accessed 2/11/2019.
  • Lupus Foundation of America. The antinuclear antibody (ANA) test. Accessed 2/11/2019.

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