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Sample

Purpose of the test

  1. For the diagnosis of Systemic lupus erythematosus (SLE ).
  2. Positive in other autoimmune diseases.

Precautions

  1. Drugs may cause false positive tests like aminosalicylic acid, chlorothiazide, procainamide, acetazolamide, penicillin, phenytoin sodium, and griseofulvin. 
  2. Drugs may cause false negative test like steroids.
  3. This test may be positive after the viral infection and some of the chronic infection.

Pathophysiology

  1. The antinuclear antibodies are produced in connective tissue diseases (autoimmune diseases ) against various antigens in the nucleus like RNA, DNA, histones, and ribonucleoprotein.
  2. Autoantibodies are directed against nuclear material (ANA) or against cytoplasmic material called anti-cytoplasmic antibodies.
  3. The major antinuclear antigens are:
    1. DNA (double and single-stranded).
    2. Histones.
    3. Nuclear proteins.
    4. RNA
      1. 95% of SLE patients shows ANA.

  1. This ANA is not specific for SLE, so it has to be supplemented by other tests.
  2. Fluorescent staining under an ultraviolet microscope shows different patterns and increase the specificity of this test.
  3. Fluorescent patterns show different staining in the nucleus e.g.:
    1. The homogeneous pattern is seen in SLE and mixed connective tissue disease.
    2. Peripheral outline only is seen in SLE.
    3. The speckled pattern has seen other autoimmune diseases like SLE, Sjogren’s syndrome, Scleroderma, Rheumatoid arthritis., and mixed connective tissue disease.
    4. The nuclear pattern is seen in Scleroderma and Polymyositis.

  1. ANA is gamma globulin and belongs to more than one type of immunoglobulin.
  2. There are ANA-negative cases of SLE.
    1. Some believe that negative ANA excludes the SLE.
  1. Diseases with positive antinuclear antibodies.
Diseases Positivity of ANA % another source positivity %
SLE 95    90 to 100
Sjogren's syndrome 60 85
Scleroderma 70 88
Dermatomyositis 30  
Rheumatoid arthritis 30 55
Polyarteritis 10  
Juvenile arthritis   22
Mixed connective tissue disease   100

Normal

Significance

  1. It helps in the diagnosis of Autoimmune diseases and particularly Systemic lupus erythematosus (98%) but with poor specificity.
  2. This test is positive 30 to 50% in other autoimmune diseases such as Rheumatoid arthritis, Sjogren’s syndrome ( 70 %) and Polymyositis and other related diseases.

The positive or increased level of ANF:

  1. SLE.
  2. Rheumatoid arthritis.
  3. Polyarteritis Nodosa
  4. Dermatomyositis.
  5. Sjogren’s syndrome.
  6. Other autoimmune diseases.
  7. Cirrhosis.
  8. Chronic hepatitis.
  9. Leukemia.

                     

                                                                                   The nucleus is pushed by the antinuclear antibody.


Possible References Used

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