Overview
Anti-nuclear antibodies bind to antigens within the nucleus of human cells, including nucleic acid, histone, chromatin and proteins.
When present in compatible clinical circumstances, ANAs can be very useful in the diagnosis of certain connective tissue diseases and inflammatory myopathies.
Interpretation
- The reported titre is the final level of dilution at which the ANA remains positive. the threshold for a 'positive' result is varied but may be e.g. >1:160.
Causes of Elevated ANA
Rheumatic
- Systemic lupus erythematosus
- Scleroderma / systemic sclerosis
- Polymyositis / dermatomyositis
- Juvenile idiopathic arthritis
- Mixed connective tissue disease
- Sjögren's syndrome
- Rheumatoid arthritis
Non-Rheumatic
- Thyroid disease - Hashimoto's, Grave's
- Hepatitis - autoimmune or viral
- Chronic infection
- Malignancy
ANA Staining Pattern
The morphology of anti-nuclear antibody staining on indirect immunofluorescence may provide a clue as to the type of antibodies present.
Interpretation
- Homogenous - SLE, drug-induced lupus, juvenile idiopathic arthritisAntibodies vs dsDNA, nucleosomes or histones
- Speckled - SLE, Sjogren's, dermatomyositis, scleroderma, mixed connective tissue diseaseAntibodies vs SSa (Ro), SSb (La), RNP, RNA polymerase III, SCL-70, Mi2, Ku
- Nucleolar - scleroderma, dermatomyositis / polymyositisAntibodies vs PM-Scl, fibrillarin, Th/To
- Centromere - limited cutaneous sclerodermaAntibodies vs CENP-B
- Cytoplasmic - mixed connective tissue disease, anti-synthetase syndromeAntibodies vs Jo1
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