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Autoimmune Screen
Autoimmune Screen

Antineutrophil Cytoplasmic Antibodies

September 12th, 2020


Anti-neutrophil cytoplasmic antibodies (ANCAs) are antibodies directed toward cytoplasmic granules of neutrophils and monocytes.
  • Assays

  • Immunofluorescence (indirect) - measures distinctive cytoplasmic (c-ANCA) or perinuclear (p-ANCA) patterns that are not specific to a single antigen
  • ELISA (direct) - measures PR3-ANCA and MPO-ANCA
ANCAs are positive in the presence of ANCA-associated small-vessel vasculitis, though may also be positive in other disease. As such, a high clinical suspicion should be present before ordering the test.
  • Interpretation

  • c-ANCA (cytoplasmic) - directed against proteinase 3 (PR3) and several other moleculesStrongly associated with granulomatosis with polyangiitis (previously Wegener's granulomatosis)
  • p-ANCA (peripheral) - directed against myeloperoxidase (MPO) and several other moleculesLess specific, but most strongly associated with microscopic polyangiitis
  • Causes of Positive ANCAs

  • ANCA-Associated Vasculitis

  • Granulomatosis with polyangiitis (previously Wegener's granulomatosis)
  • Microscopic polyangitis (MPA)
  • Eosinophilic granulomatosis with polyangiitis (previously Churg-Strauss syndrome)
  • Drug-induced vasculitis
  • Other

  • Infective endocarditis
  • Tuberculosis
  • Primary sclerosing cholangitis (PSC)
  • Pulmonary fibrosis
  • Ulcerative colitis
  • Rheumatoid arthritis
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