Antinuclear antibodies $$$

ANA are the antibodies (gamma globulins) important for diagnostics; they include all autoantibodies against nuclear antigens in the nucleus and cytoplasm. In contrast to the original definition, the term "ANA" also includes antibodies against cytoplasmic and mitochondrial target antigens. ANA include, for example, DNA, histones (H1, H2A, H2B, H3, H4), DNA-histone complexes, ribonucleoproteins (U1-RNP, Sm, La (SS-B), Ro (SS-A), Jo-1 (histidyl-t-RNA transferase)), and non-histone proteins (centromere-AK, Scl-70, PM-1, Mi-2).

See also Autoantibodies.

Extractable antinuclear antibodies(ENA) are a diagnostically important subgroup.

Detection by indirect immunofluorescence methods (considered the gold standard); HEp-2 cells form the substrate. The fluorescence pattern gives an indication of the specificity of the antibody. Nuclear, cytoplasmic and mitotic patterns are distinguished. Diagnosis is performed according to ICAP, an international standard (ICAP = International Consensus on Antinuclear Antibody Pattern), which distinguishes 20 discrete fluorescence patterns (ICAP code).

Furthermore, ELISA techniques as well as immunoblot procedures(Western blot) can be used.

Standard value: The standard value is positive from a titer of 1: 160 (ANA with low affinity is often detected in healthy people).

Pathologically elevated: Felty syndrome, systemic lupus erythematosus, autoimmune hepatitis, drug-induced discoid and subacute cutaneous lupus erythematosus, systemic sclerosis, multiple non-inflammatory diseases, juvenile chronic arthritis, poly-/dermatomyositis.

In older people, positive findings without detectable disease (frequency varies according to literature. Up to 30% in people >60 years; up to 8% in people <60 years).

• Diseases in which ANA determination is important for diagnosis/progression control:
  • Systemic lupus erythematosus (95-100%)
  • Drug-induced LE (95-100%)
  • Congenital lupus erythematosus
  • Systemic scleroderma
  • Polymyositis (mostly Jo-1 positive)
  • Dermatomyositis (usually Jo-1 positive)
  • Primary Sjögren's syndrome (mostly SS-A (Ro) and SS-B-(La) positive)
  • Mixed Connective Tissue Disease (mostly RNP positive, typically in high concentration).
  • CREST syndrome (usually centromere-positive).
• ANA may be present as an associated phenomenon; they have no diagnostic significance in the following diseases:
  • Chronic active hepatitis (especially hepatitis C).
  • Polyarthritis, chronic (rheumatoid arthritis) ("rheumatism")
  • Arthritis, psoriatic
  • Felty syndrome (60-95%)
  • Hemolytic anemia (50%)
  • Juvenile chronic arthritis
  • Rheumatoid arthritis ( 20-50%)
  • Polyarteritis nodosa, systemic (20%)
  • Pulmonary fib rosis (fibrosing alveolitis)
  • Myasthenia gravis
  • Primary biliary cirrhosis (40%)
  • alcohol toxic liver cirrhosis (30%)
  • autoimmune hepatitis (60-100%)
  • Viral hepatitis (30%)
  • malaria (30%)
  • leukemias (30-70%)
  • Sarcoidosis.