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Antinuclear Antibodies

 

A diagnosis is NEVER made based on antibodies.

Antibodies directed against a variety of nuclear antigens, including nucleic acids, histones and components of the centromere.

 

Antibodies are sensitive markers for SLE (over 95%), but specificity is low - are found in 3-5% of healthy people and with other diseases. If negative, the need to persue other testing is not necessary.

Can also be positive in lymphoproliferative diseaae, chronic infections, a number of drugs, and other things.

Conditions associated with a positive ANA include

• drug-induced lupus (100%)
• chronic active hepatitis (100%)
• SLE (98%)
• systemic sclerosis (95%)
• mixed connective tusse disease (95-99%)
• polymyositis/dermatomyositis (90%)
• Sjogren's syndrome (80%)
• rheumatoid arthritis (60%)
• myasthenia gravis (50%)
• diabetes (25%)

 

Protocol

Cells from a human tumor cell line are placed on a slide and coated with serial dilutions of the patient’s serum. Using fluorescein-labeled anti-human IgG to detect the bound autoantibodies, the technician reports the pattern of staining.

 

Staining Patterns are important, but have largely been replaced by extractable nuclear antigens

•  A diffuse pattern is binding across the nucleus, with antibody binding to DNA itself specificity 95%, sensitivity 30-70%.
• a peripheral pattern, staining around the nucleus is also specific for SLE.

 

 

Interpretation
A positive titer is > 1/100. 
Specific Autoantibodies
Immunoassay techniques allow detection of antibodies against cellular antigens.