Anti-DNA, (anti-double-stranded DNA antibodies, Anti-ds-DNA Ab) and Their Significance
- This test is done on the Serum of the patient.
- The serum can be stored at -20 °C.
- Take 3 to 5 ml of blood in the disposable syringe. Keep the syringe for 15 to 30 minutes and then centrifuge for 2 to 4 minutes. In this way, you can get a clear serum.
- Also, these anti – DNA antibodies can be detected by biopsy, e.g, of kidney or skin.
Purpose of the test (Indications)
- This is specific for the diagnosis of systemic lupus erythematosus ( SLE ).
- This test can be used for the follow-up of SLE cases.
- It is indicated in the positive Antinuclear antibody (ANA) test.
- Avoid drug hydralazine and procainamide, which increase the DNA level.
- A radioactive scan in the last week may alter the result.
- These antibodies are found in 60 to 80 % of patients with active SLE.
- Anti-dsDNA is more specific for the diagnosis of SLE (Systemic lupus erythematosus).
- These are a group of autoantibodies seen in autoimmune diseases.
- These antibodies are produced against antigens in the nucleus like:
- Double and single-stranded DNA antigens.
- The anti-DNA antibody is a subtype of the Antinuclear antibody (ANA).
- The most common is an antibody against the double-stranded DNA (anti-dsDNA, DSDNA)
- The second antibody is against the single-stranded DNA (ant-ssDNA, SSDNA) is less sensitive and specific.
- These antigen-antibody complexes cause damage to tissue by complement system activation.
- When a compliment is activated, that may cause local or systemic damage.
- High titers of ant-DNA are characteristic of SLE.
- Low to intermediate levels are seen in other autoimmune diseases, chronic hepatitis, biliary cirrhosis, and infectious mononucleosis.
- Anti-DNA titer decreases with successful therapy of the SLE.
- It increases if there is a recurrence of SLE.
- It is near to normal in the case of dormant SLE.
Systemic lupus erythematosus has the following presentation:
- These patients may have a low-grade fever.
- This patient may have persistent fatigue and weakness.
- There is muscle pain.
- There may be an arthritis-like pain in one or more of the joints, except small joints.
- There is skin sensitivity to light.
- There are butterfly rashes on the nose and cheek.
- There is weight loss.
- There is hair loss.
- There may be numbness and tingling in the hands or feet.
- Multiple organ diseases involve the kidneys, heart, lung, blood vessels, and central nervous system.
Normal Anti-dsDNA antibodies:
- Negative : < 70 IU/mL
- Borderline : 70-200 IU/mL
- Positive : > 200 IU /mL
- Negative = <25 IU by ELIZA
- Borderline = 25 to 30 IU
- Positive = 31 to 200 IU
- Strongly positive = >200 IU
- Anti-DNA is useful to diagnose and follow up SLE.
Association of Anti-dsDNA antibody for various diseases DNA-antibody (anti-dsDNA)
- SLE = 60% to 70% (range = 35% to 75%)
- Rheumatoid arthritis = 5% to 40%
- MCTD (mixed connective tissue disease) = 11% to 25%
- Sjogren’s syndrome = 5% to 55%
- The level of this antibody correlates with disease activity and the presence of kidney disease (glomerulonephritis).
- This test may be positive in chronic hepatitis, primary biliary cirrhosis, and infectious mononucleosis.
- Few drugs may give a positive test like procainamide and hydralazine.
The pattern on biopsy material:
- This test can be done by fluorescent microscopy and will see a different pattern in various diseases in tissue biopsy.
- This ANA pattern is associated with only one autoantibody or specific disease. These patterns are:
- Rim or peripheral pattern:
- This is seen at the nuclear border.
- This is thought to be produced against several nucleoproteins, including sNP, Single-stranded DNA (ssDNA), and histones.
- A high titer of ANA (1:160 or greater) with the rim is strongly suggestive of SLE.
- If the ANA antibody titer is low, then it is not helpful to diagnose SLE.
- Solid or homogenous pattern:
- This is seen throughout the nucleus.
- This is the second most common ANA pattern.
- ANA can produce this pattern against dsDNA, ssDNA, sNP, and histones.
- This pattern is most frequently seen in SLE but not diagnostic.
- This may be seen in other rheumatoid-collagen diseases.
- The ANA titer is usually <1:160 in diseases except for SLE.
- Speckled pattern:
- There are small fluorescent dots throughout the nucleus.
- There is no involvement of the nucleoli.
- This is the most common ANA pattern.
- The ANAs are produced against acidic nuclear proteins ENA (Sm and RNP), SS-A and SS-B, histones, and scleroderma-70 (Scl-70).
- It is seen in 25% of the SLE cases.
- ANA against Sm strongly suggests SLE, while ANA against RNP suggests mixed connective tissue disease (MCTD).
- ANA against SS-B suggests Sjogren’s disease, and ANA against Scl-70 suggests scleroderma.
- Nucleolar pattern:
- This is only seen in the nucleolus, and there are several irregulars shapes and different sizes.
- This pattern is due to ANA against the nucleolar ribonucleic acid (RNA, 4-6s RNA).
- It is suggestive of scleroderma 55% to 90% of the cases when the titer is high.
- The low titer is found in the SLE and other collagen diseases.
- Rim or peripheral pattern:
Table of a pattern of immunofluorescence staining in various autoimmune diseases:
|SLE||nuclear pattern, homogeneous, peripheral, and speckled|
|Scleroderma||homogeneous, peripheral, and speckled|
|Primary biliary cirrhosis||Mainly Nucleolar|
|Rheumatoid arthritis||homogeneous, peripheral, and speckled|
SLE nuclear pattern
- Anti-double-stranded DNA antibody (anti-dsDNA) is more specific than simple anti-DNA antibodies.
Various cytoplasmic and nuclear protein positivity in SLE:
Test parameters Positivity in SLE ANA screening >95% (another reference 99%) DNA (native, Anti-dsDNA)) 60% (another reference 40%) Histones 30% (another reference 70%) Sm (Smith antigen) 30% Nuclear RNP (ribonucleoprotein) 40% to 50% (another reference 30%) Scl-70 (scleroderma) Rare SS-A (Ro- Sjogren’s syndrome) 40% to 60% (another reference 30%) SS-B (La) 15% (another reference 30%) Centromere Rare Nucleolar antigen 25%
Increased Anti-DNA antibody level seen in:
- Systemic lupus erythematosus.
- Other autoimmune diseases.
- Biliary Cirrhosis.
- Chronic hepatitis.
- Infectious mononucleosis.