The immune system is responsible for defending us against attacks from foreign cells and organisms, such as bacteria, viruses, etc. But it often goes haywire and sees some of its own tissues as foreign. The production of antibodies against the body’s own tissues is the cause of a large number of auto-immune diseases that manifest as inflammation, muscle and joint pain, and fatigue. ANAs (antinuclear antibodies) comprise a wide variety of autoantibodies that specifically target components of the cell nucleus. The test examines the quantity of antibodies present: a titre of 1/640 indicates that there are 4 times more ANAs than a titre of 1/160. The test also indicates how these antibodies are distributed—diffuse distribution, in the form of pellets, granules that are located on a particular nucleus structure called a nucleolus.
Test results are interpreted by a hematologist, taking into account the titre and type of antibody distribution and, in certain cases, the subject’s age (negative result, result suggestive of an autoimmune disease, etc.). When the result is positive, the hematologist will suggest tests (anti-ENA, anti nDNA, etc.) that will help better identify the nature of the autoimmune disease involved (systemic lupus erythematosus, Sjögren’s syndrome, rheumatoid arthritis, scleroderma, polymyositis, mixed connective tissue disease, etc.).