Anti-Neutrophil Cytoplasmic Antibody (Anca)

ANTI-NEUTROPHIL CYTOPLASMIC ANTIBODY (ANCA)


ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES(ANCA)

  • ANCA’s are the heterogeneous group of autoantibodies directed against antigens which are found within primary granules of neutrophil and in the lysosomes of monocytes and in endothelial cells. 
  • Description based on immunofluorescence pattern of staining of ethanol-fixed neutrophils.

With immunofluorescence two principal patterns are recognized:

1.  Anti-proteinase-3 (PR3-ANCA)

  • Previously referred to as “Cytoplasmic (c-ANCA)” (image A)
  • This shows cytoplasmic localization of staining and target antigen is proteinase-3 (PR3), a neutrophil granule constituent.
  • Typically found in Wegener’s granulomatosis(95%)

2.  Anti-myeloperoxidase (MPO-ANCA) 

  • Previously referred to asPerinuclear staining (p-ANCA)” (image B)
  • This shows perinuclear staining and target antigen here is myeloperoxidase (MPO).

Typically found in

  • Microscopic polyangiitis
  • Churg-Strauss syndrome
  • Idiopathic crescentic glomerulonephritis
  • Goodpasture’s syndrome.
  • Also associated with certain non-vasculitic entities (rheumatic & nonrheumatic autoimmune diseases, Inflammatory bowel diseases.
  • Infections such as endocarditis & hepatitis B, bacterial airway infection in patients with cystic fibrosis.
  • Remember that either of these antibodies may occur in a patient with ANCA associated small vessel vasculitis.

Exam Important

  • 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 non-vasculitic entities such as rheumatic and nonrheumatic autoimmune diseases.
    • ANCA associated with Wegner’s granulomatosis is c-ANCA.
  • pANCA is sensitive and specified for Idiopathic crescentic glomerulonephritis.
  • ANCA positive vasculitis is Wegener’s Granulomatosis, Churg-Strauss syndrome, Microscopic PAN
  • Goodpasture syndrome is positive for pANCA.
  • The most likely diagnosis in 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 polyangiitis.
  • 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 the 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 up to 95% of cases of Wegener’s granulomatosis.
Don’t Forget to Solve all the previous Year Question asked on ANTI-NEUTROPHIL CYTOPLASMIC ANTIBODY (ANCA)

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