Antinuclear Antibodies (ANA)

Systemic autoimmune rheumatic diseases are characterized by elevated levels of autoantibodies produced against intracellular proteins and nucleic acids (DNA, RNA). These are called autoantibodies Antinuclear Antibodies (ANA), Because they are directed mainly against nuclear antigens.

Detection / determination of ANA in the blood is the best screening test for the diagnostics of systemic connective tissue diseases. The prevalence of ANA in such patients is 20 to 100%.

To identify rheumatic diseases, it is important to distinguish between different antibodies in the ANA group. Two main categories of antinuclear antibodies are currently described:

1. Autoantibodies targeting DNA and histones.

2. Autoantibodies targeted - soluble nuclear antigens.

Target antigens of antinuclear antibodies are highly diverse. Therefore, if there is a positive result in the study of general antinuclear antibodies, it is necessary to test for specific antibodies that will help us diagnose a specific autoimmune disease.

Types of antinuclear antibodies:

• Anti-U1nRNP antibodies Target: Small ribonucleoprotein (snRNP) antigen (a set of RNA and its binding protein). Characteristic of Sharp disease (connective tissue disease).
• Anti-Sm antibodies Target: Sm antigen (nuclear protein) is characteristic of systemic lupus erythematosus.
• Anti-SS-A (Ro) antibodies Target: SS-A (Ro) (A antigen associated with Sjენისgren's syndrome). Characteristic of Sjენისgren's syndrome and systemic lupus erythematosus. They have the ability to cross the placental barrier, after which they enter the fetal bloodstream and cause congenital systemic lupus erythematosus or congenital AV block, which is why it is recommended to test for these antibodies in pregnant women.
• Anti-SS-B (La) antibodies Target: A protein involved in the production of RNA polymerase III (soluble substance B). Characteristic of Sjენისgren's syndrome.
• Anti-Ro52 antibodies - It is non-specific and is found in both rheumatic and non-rheumatic diseases. It is often characteristic of Sjogren's syndrome.
• Anti-Scl-70 antibodies - Characteristic for systemic scleroderma (progressive systemic sclerosis).
• Anti-PM-Scl antibodies Target: A protein complex involved in ribosome synthesis. Characteristic of the complex form of systemic scleroderma with poliomyositis / dermatomyositis.
• Jo-1 antibodies - is a serological marker of dermatomyositis / poliomyositis. The presence of these antibodies is associated with a more severe form of the disease and can be detected as soon as symptoms appear.
• Anti-CENP In Antibodies Target: A protein involved in cell division. CENP B is a serological marker for CREST syndrome (a subtype of progressive systemic scleroderma).
• PCNA antibodies Target: A protein involved in DNA replication and repair and cell cycle regulation. It is found in 3% of patients with systemic lupus erythematosus.
• Anti-double-stranded DNA antibodies - is a diagnostic marker of systemic lupus erythematosus, is characterized by high specificity (found in 30-90% of patients with lupus erythematosus). It is also used to monitor the clinical activity of the disease. A small percentage can be found in the case of drug-induced lupus erythematosus, rheumatoid arthritis and scleroderma.
• Antinucleosomal antibodies - They can be detected in systemic lupus erythematosus, prior to double-stranded DNA antibodies.
• Antihistone antibodies - Target: Histons. Is found in 95% of drug-induced systemic lupus erythematosus.
• Ribosomal P-protein antibodies - is a marker of neurolupus (damage to the central and peripheral nervous system caused by lupus erythematosus).
• Anti-mitochondrial AMA M2 antibodies Target: Enzyme pyruvate dehydrogenase. Its elevated titer confirms the diagnostics of primary biliary cirrhosis. Has a prognostic value in patients with signs of biliary stasis and indicates the risk of developing biliary cirrhosis.
• Anti-DFS70-antibodies - Associated with atopic dermatitis and prostate cancer. Its highest prevalence is confirmed in patients with Vogt-Harada syndrome (66.7%), autoimmune thyroiditis (55%) and atopic dermatitis (30%).

When should we test for antinuclear antibodies?

• The doctor suspects autoimmune systemic disease of the connective tissue (collagenosis).
• To diagnose and evaluate the activity of diseases such as systemic lupus erythematosus, progressive systemic sclerosis, Sjogren's syndrome, polymyositis / dermatomyositis and Sharp syndrome.

In the presence of such symptoms as:

• Butterfly redness on the face and décolleté;
• Feeling of tightness;
• Feeling of tightness in the face and fingers;
• Increased photosensitivity;
• Raynaud's phenomenon (paleness, bruising and redness of the face, pale fingers in the cold);
• Swelling and pain in the joints;
• The appearance of red spots on the skin;
• Weakness of thigh and shoulder muscles and more.

How to prepare for the test?

Testing is preferred on empty stomach .

Food, water and other products are not affected by the test results.

Research material

Venous blood

Possible interpretation of the results

Positive result Confirms the presence of specific antibodies.

Weak signal Indicates that the presence of autoantibodies is unclear and questionable. Depending on the patient's symptoms, the test may be repeated every 1-2 months.

Negative result Indicates the absence of specific autoantibodies.

Resources

https://www.synevo.bg/ana-imunoblot/