Anti-DNA, (anti-double-stranded DNA antibodies, Anti-ds-DNA Ab)

Sample

1. This test is done on the Serum of the patient.
2. 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 can get a clear serum.
3. Also, these anti – DNA antibodies can be detected by biopsy e.g of kidney or skin.

Purpose of the test (Indications)

1. This is specific for the diagnosis of systemic lupus erythematosus ( SLE ).
2. This test can be used for the follow-up of SLE cases.
3. It is indicated in the positive Antinuclear antibody (ANA) test.

Precaution

1. Avoid drug hydralazine and procainamide which increases the DNA level.
2. A radioactive scan in the last week may alter the result.

Pathophysiology

1. These antibodies are found in 60 to 80 % of patients with active SLE.
   1. Anti-dsDNA is more specific for the diagnosis of SLE (Systemic lupus erythematosus).
2. These are a group of autoantibodies, seen in the autoimmune diseases.
3. These antibodies are produced against antigens in the nucleus like:
   1. Histones.
   2. Double and single-stranded DNA antigens.
   3. Ribonucleoproteins.

4. The anti-DNA antibody is a subtype of the Antinuclear antibody (ANA).
5. The most common is an antibody against the double-stranded DNA (anti-dsDNA, DSDNA)
   1. The second antibody is against the single-stranded DNA (ant-ssDNA, SSDNA) is less sensitive and specific.
6. These antigen-antibody complexes cause damage to tissue by complement system activation.
   1. When a compliment is activated that may cause local or systemic damage.

7. High titers of ant-DNA are characteristic of SLE.
   1. Low to intermediate levels are seen in other autoimmune diseases, chronic hepatitis, biliary cirrhosis, and infectious mononucleosis.
8. Anti-DNA titer decreases with successful therapy of the SLE.
   1. It increases if there is a recurrence of SLE.
   2. It is near to normal in case of dormant SLE.

Systemic lupus erythematosus has the following presentation:

1. These patients may have a low-grade fever.
2. This patient may have persistent fatigue and weakness.
3. There is muscle pain.
4. There may be an arthritis-like pain in one or more of the joints with the exception of small joints.
5. There is skin sensitivity to light.
6. There are butterfly rashes on the nose and cheek.
7. There is weight loss.
8. There is hair loss.
9. There may be numbness and tingling in the hands or feet.
10. This is multiple organ diseases involving the kidneys, heart, lung, blood vessels, and central nervous system.

Normal

Source 2

• Negative : < 70 IU/mL
• Borderline : 70-200 IU/mL
• Positive : > 200 IU /mL

Source 4

• Negative = <25 IU by ELIZA
• Borderline = 25 to 30 IU
• Positive = 31 to 200 IU
• Strongly positive = >200 IU

Significance:

1. Anti-DNA is useful to diagnose and follow-up of SLE.
2. The level of this antibody correlates with disease activity and the presence of kidney disease (glomerulonephritis).
3. This test may be positive in chronic hepatitis, primary biliary cirrhosis, and infectious mononucleosis.
4. 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 case of tissue biopsy.

Table of a pattern of immunofluorescence staining

Disease	Nuclear Pattern
SLE	nuclear pattern, homogeneous, peripheral, and speckled
Scleroderma	homogeneous, peripheral, and speckled
Primary biliary cirrhosis	Mainly Nucleolar
Rheumatoid arthritis	homogeneous, peripheral, and speckled

• Anti-double-stranded DNA antibody (anti-dsDNA) is more specific than the simple anti-DNA antibodies.

Increased Anti-DNA antibody level seen in:

1. Systemic lupus erythematosus.
2. Other autoimmune diseases.
3. Biliary Cirrhosis.
4. Chronic hepatitis.
5. Infectious mononucleosis.

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