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Antinuclear antibody test
Make it clearer
In an autoimmune disease the body's defenses attack its own tissue. Antinuclear antibodies, abbreviated ANA, are autoantibodies: antibodies aimed at material in the nucleus of the person's own cells, the center where DNA lives. Looking for them is usually the first step when a systemic autoimmune connective tissue disease is suspected, connective tissue being what supports and holds the rest of the body together.
The test is done by exposing the person's serum, the liquid part of blood, to HEp-2 cells fixed on a slide. If antibodies are present, they stick to the nucleus and light up under the microscope in distinct shapes. The fluorescent pattern shows where in the nucleus the antibody attached. That technique is called indirect immunofluorescence, and it is the reference standard.
And here is what matters: 20% to 30% of the general population has detectable ANA. That is why a positive result is not read on its own, but together with what the person actually has.
In brief
Antinuclear antibodies target material in the cell nucleus, and testing for them is usually the first step in diagnosing a systemic autoimmune connective tissue disease.
Serum is applied to fixed HEp-2 cells, and bound antibodies produce fluorescent patterns; this indirect immunofluorescence is the reference standard.
The fluorescent pattern shows where in the nucleus the antibody attached.
20% to 30% of the general population has detectable titers, so a positive result is interpreted together with the clinical manifestations.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingBiochemistry, Antinuclear Antibodies (ANA), StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
Updated