ANA or anti-nuclear antibodies are a group of special autoantibodies directed against various components of the cell nucleus. The presence of ANA is associated with several autoimmune diseases but is most commonly seen in systemic lupus erythematosus (SLE). Over 90% of SLE patients test positive for ANA.
Other conditions in which the ANA test may be positive include Sjögren’s syndrome (between 40% and 70% of patients with this condition have a positive ANA test result), and systemic sclerosis (about 60% to 90% of people with scleroderma test positive for ANA). A positive ANA result may eventually occur in people with Raynaud’s disease, rheumatoid arthritis, dermatomyositis or polymyositis, mixed connective tissue disease, and other kind of autoimmune disease.
ANA can be detected by indirect immunofluorescence assays (IFA) on HEp-2 cells fixed to glass slides or by immunoassays, e.g. ELISA or immunoblot. In ANA detection IFA and immunoassays complement each other: one test is used for screening, the other for confirmation of positive or ambiguous test results.
For further differential diagnosis single ANA subspecies may be analysed individually by enzyme-linked immunosorbant assay or blot tests, e.g. SS-A antibodies (Ro) and SS-B antibodies (La) when Sjögren’s syndrome is suspected, or anti-Scl-70 antibodies and anti-centromere assays in scleroderma.
A positive ANA test is not necessarily related to an autoimmune disease: about 15% of completely healthy persons have a positive ANA test.
Tests for ANA detection offered by ORGENTEC Diagnsotika
ANA-9-Line (ORG 710)
Tests for Indirect Immunofluorescence Assays (IFA):