Antibodies against nuclear antigens (ANA) are directed against various cell nuclear components (biochemical substances in the cell nucleus). These encompass nucleic acids, cell nuclear proteins and ribonucleoproteins. The ANA profile II used for detection autoantibodies against individual or several cell nuclear autoantigens is an essential element in the diagnosis of autoimmune diseases, particularly rheumatic diseases i.e. Anti-nRNP/Sm, Anti Sm, Anti SS-A, Anti Ro-52, Anti SS-B, Anti Scl-70, Anti PM-Scl, Anti Jo-1, Anti CENP B, Anti PCNA, Anti dsDNA, Anti Nucleosomes, Anti Histones, Anti Ribosomal P-Protein, Anti AMA-M2, Anti DFS70.
The investigation of ANA and subsequent differentiation within the ANA or ENA spectrum contributes greatly to establishing a diagnosis, particularly in the following rheumatic diseases:
- Systemic lupus erythematosus (SLE)
- Sharp syndrome (mixed connective tissue disease = MCTD)
- Sjögren’s syndrome
- Systemic sclerosis (systemic scleroderma, SSC)
- Limited form of systemic sclerosis (CREST syndrome)
- Myositis (poly-/dermatomyositis)
- Rheumatoid arthritis
- Overlap syndromes
- Primary biliary cholangitis

The serological detection of autoantibodies against individual or several cell nuclear autoantigens is an essential element in the diagnosis of autoimmune diseases.  The frequency (prevalence) of anti-nuclear antibodies in inflammatory rheumatic diseases in between 20% and 100% (in rheumatoid arthritis between 20% and 40%).  Therefore, differential ANA diagnostics to detect autoantibodies against different nuclear antigens is indispensable for the identification of individual rheumatic diseases. The ANA profiles offer innovative test combination based on the lineblot technology.  Positive test resulst provide important serodiagnostic information for the diagnosis of the rheumatic diseases, as well as further autoimmune disease such as primary biliary liver cholangitis (PBC). However, antibodies against nuclear antigens are detectable in subjectively healthy individuals, usually at a low level.  This finding is more common in women than men and the frequency of a detectable ANA in healthy women over 40 years of age may approach 15% to 20%. ANA may also be detectable following viral illnesses, in chronic infections, or in patients treated with many different medications.  A diagnosis should not be made based on a single test result. The clinical symptoms of the patient should always be taken into account along with the serological results by the physician.