ANCA(Antineutrophil Cytoplasmic Antibody)

ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES(ANCA)
  • ANCA are heterogenous group of autoantibodies directed against antigens which are found within the primary granules of neutrophil and in the lysosomes of monocytes and in EC's. The description of these autoantibodies is based on the immunofluorescence pattern of staining of ethanol fixed neutrophils.
With immunofluorescence two principal patterns are recognized:
1. Cytoplasmic (c-ANCA):

  • This shows cytoplasmic localization of the staining and the target antigen for this type of autoantibody is — proteinase-3 (PR3), a neutrophil granule constituent.
2. Perinuclear staining (p-ANCA)
  • This shows perinuclear staining and the target antigen here is myeloperoxide (MPO).
Remember that either of these antibodies may occur in a patient with ANCA associated small vessel vasculitis but
  1.  cANCA Typically found in
  • Wegener's granulomatosis(95%)
  1. pANCA Typically found in
  • Microscopic polyangiitis
Also seen in :
  • Churg-Strauss syndrome
  • Idiopathic crescentic glomerulonephritis
  • Goodpasteur's syndrome.
  • pANCA's are also associated with certain non-vasculitic entities such as certain rheumatic and nonrheumatic autoimmune diseases, Inflammatory bowel diseases, certain drugs, infections such as endocarditis and hepatitis B 
• bacterial airway infection in patients with cystic fibrosis.
Exam Question of:
  • Hepatitis B is associated with an immune-mediated vasculitis characterized by p-ANCA antibodies.
  • C- ANCA positivity indicates, antibody formed against Proteinase 3.
  • Proteinase-3, in neutrophil azurophilic granules, is the major cANCA antigen.
  • The major target for pANCA is the enzyme myeloperoxidase.
  • There are two major categories of ANCA.
  • pANCA pattern of staining has been associated with nonvasculitic entities such as rheumatic and nonrheumatic autoimmune diseases.
  • ANCA associated with Wegner's granulomatosis is c ANCA.
  • pANCA is sensitive and specified for Idiopathic cresentic glomerulonephritis .
  • ANCA positive vasculitis are Wegener's Granulomatosis , Churg-strauss syndrome,Microscopic PAN
  • Goodpasture syndrome is positive for pANCA.
  • The most likely diagnosis iin a patient presenting with respiratory symptoms i.e. cough, hemoptysis and glomerulonephritis and C­ANCA levels in serum found to be raised is Wegener's granulomatosis.
  • ANCA associated with crescentic glomerulonephritis is seen in Wegener's granulomatosis , microscopic polyangitis.
  • The most likely diagnosis in a 20 year old male presenting with mucus and repeated gastrointestinal bleeding and positive for ANCA is Ulcerative Colitis.
  • Likely diagnosis in a patient presenting with hemoptysis and hematuria few weeks after a respiratory tract infection with presence of ANCA antibodies is Goodpasture's syndrome. cANCA Positivity is specific for Wegener's granulomatosis.
  • p-ANCA is characteristic for Microscopic Polyangitis.
  • c-ANCAs are present in upto 95% of cases of Wegener's granulomatosis.
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