3 ANCA Test

The full form of ANCA is anti-neutrophil cytoplasmic antibodies.  This test can detect the occurrence of specific auto-immune diseases like Wegener’s Granulomatosis, Churg-Strauss Syndrome, Microscopic Polyangitis and so on.  The test is performed by separating the type of white blood cell called neutrophils.  Dye is applied to neutrophils that will appear fluorescent in UV light.  The specific characters of these illuminated substances are then studied by their detailed examination under the microscope.

ANCA is divided into

  •  c-ANCA
  •  p-ANCA
  •  x-ANCA

This classification is based on the pattern of staining on neutrophils and the main target antigen.
This pattern is due to the bonding of the ANCA to antigen targets throughout the neutrophil cytoplasm. PR3 is the antigen target of ANCA in people suffering from Wegener’s granulomatosis. Most commonly PR3 is the antigen associated with c-ANCA pattern.

p-ANCA shows a perinuclear type of staining pattern. This type of pattern results due to the cationic property of ANCAs which targets the antigens. The most common p-ANCA target is myeloperoxidase.

ANCA which target antigens other than PR3 or myeloperoxidase results in patchy pattern and it occurs in persons suffering from non-vasulitic diseases.

3 ANCA test is usually done to check if a person has symptoms resulting from autoimmune vasculitis (swelling of the blood vessels). Wegener’s granulomatosis is a significant form of vasculitis.  

Symptoms of Wegener’s granulomatosis

Symptoms of Wegener’s granulomatosis include fever, weight loss, muscle aches and night sweats. Some examples of signs on the body include-

  • Eyes become red itchy and there might be blurry vision.
  • There may be hearing loss
  • Respiratory disorders includes running of nose
  • Abnormal quantities of protein in urine
  • Rashes on skin

Results of the tests
Positive ANCA tests helps in the diagnosis of systemic autoimmune vasculitis. The tests are done by mixing serum samples with neutrophils to make the autoantibodies that may be present to react. It is put on the slide later and stained.

This slide is observed under a microscope to check for the patterns.
If the test results are positive then another test has to be done to obtain the number of antibodies present. In this test the serum is diluted in steps and this solution is tested at various steps for the antibodies.

Additional tests can be done to check for a specific antibody. These tests are for PR3 and MPO.

 Positive PR3 tests and positive c-ANCA and p-ANCA tests are very common and they are found in almost 78 % of the people with Wegener’s granulomatosis. Positive MPO test and a positive p-ANCA are found in people suffering from microscopic polyangitis, Churg-Strauss syndrome and Goodpastures syndrome.

Top Comments

Thank you, very informative, which ag is detected by x-anca?
by rachel oommen     19-Feb-2012

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