C-ANCA

TEST DESCRIPTION :

Anti neutrophil cytoplasmic antibody (ANCA) tests are used to diagnose and monitor inflammatory activity in the primary systemic small vessel vasculitides. ANCA in these diseases is best demonstrated by using a combination of Indirect Imunofluorescence of normal peripheral blood neutrophils and ELISAs that detect ANCA specific for proteinase 3(PR3) or Myeloperoxidase (MPO)
1. c-ANCA is associated with Wegener's granulomatosis and less frequently with microscopic polyangitis.Approximately 85% of the patients with C-ANCA pattern by IFA have antibodies specific for PR3.
2- Atypical C-ANCA has no clinical significance.
3. p-ANCA is associated with microscopic polyangiitis and focal necrotizing and crescentic glomerulonephritis. Churg-Strauss syndrome is associated with p-ANCA directed against MPO. Approximately 90% of patients with a P-ANCA pattern by IFA have antibodies specific for MPO.
4. Atypical P-ANCA is described with a mixed group of inflammatory diseases e.g sclerosing cholangitis and connective tissue disorders.Antigen targets include lactoferrin,elastase,cathepsin G and BPI. Patients with a number of other diseases, such as ulcerative colitis and ankylosing spondylitis, will commonly have ANCA as well. However in these cases there is no associated vasculitis and the ANCA are thought to be incidental or epiphenomena rather than part of a disease itself.

TECHNIQUE

1-, BIOCHIP slide with Hep 2 cells, primate liver, ethanolfixed granulocytes and formaldehyde fixed granulocytes is used. The technique avoids false positive reporting of ANCA in ANA positive patients.
2-Indirect immunofluorescene, sample screening dilution used is 1:10.
Remarks:
Decision about treatments should not be soley based on results of ANCA tests.