Anti-neutrophil cytoplasmic antibodies (ANCA) are autoantibodies, with the target antigen found in the cytoplasm of neutrophils or monocytes. Measurement of anti-neutrophil cytoplasmic antibodies is indicated in patients with findings suggestive of a systemic vasculitis.
Indications for measuring ANCA:
(1) 1 or more of the following clinical findings with no other obvious cause (infection, tumor, toxin exposure, etc.)
(1a) chronic destruction of the upper airways
(1b) chronic sinusitis or otitis
(1c) subglottic tracheal stenosis
(1d) retro-orbital mass
(1e) pulmonary hemorrhage, especially in patients also with renal involvement
(1f) multiple lung nodules
(1g) glomerulonephritis, especially if rapidly progressive
(1h) mononeuritis multiplex or other peripheral neuropathy
(1i) cutaneous vasculitis with systemic features
(2) in a symptomatic patient for whom ANCA has previously been demonstrated, to distinguish between:
(2a) increased autoimmune disease activity
(2b) adverse effects of treatment
Autoimmune diseases with anti-neutrophil cytoplasmic antibodies include:
(1) Wegener's granulomatosis or its variants
(2) microscopic polyangiitis, polyarteritis nodosa
(3) Churg-Strauss syndrome
(4) idiopathic crescentic glomerulonephritis
(5) Sjogren's syndrome
(6) other autoimmune disorders such as rheumatoid arthritis and SLE
(7) Crohn's disease
(8) primary biliary cirrhosis
Because concurrent infection, tumors or other diseases can also elevated ANCA levels (cause false positive results), ANCA testing should not be done unless there is a high index of suspicion for an ANCA-associated vasculitis. A positive ANCA result by itself is not diagnostic of a vasculitis.
When measuring ANCA, both immunofluorescence and ELISA testing should be performed.
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Immunofluorescent Pattern
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Corresponding Antigen in ELISA
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cytoplasmic (c-ANCA)
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proteinase-3 (PR3)
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perinuclear (p-ANCA)
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myeloperoxidase (MPO)
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