ANCA, IIF Screen Anti-Neutrophil Cytoplasmic Antibodies

Immunology

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Description

There are two major subclasses of ANCA, characterised by staining patterns found when using fixed human neutrophils as substrate under Indirect Immunofluorescence (IIF): 1. C-ANCA (Cytoplasmic or Classical Staining ANCA), denotes a granular cytoplasmic staining pattern on ethanol fixed neutrophils, with some interlobular accentuation. C-ANCA are principally directed against a 29,000 Dalton serine protease, proteinase 3 (PR3) present in the azurophil granules in the cytoplasm of human neutrophils. Other C-ANCA specificities have been detected for cationic protein 57 (CAP57) and cathepsin G. C-ANCA positive is suggestive but not diagnostic of GPA, MPA (and its renal limited variant) and EGPA. C-ANCA positive results must be followed up by ELISA tests for anti-MPO and anti-PR3 [1]. 2. P-ANCA (Perinuclear Staining ANCA), denotes a staining pattern present in the perinuclear space of the cytoplasm of ethanol fixed neutrophils. P-ANCA are principally directed against myeloperoxidase (MPO), which is also found in azurophil granules in the cytoplasm of human neutrophils. Other P-ANCA antigen specificities are for elastase and lactoferrin. P-ANCA is associated in MPA and in some cases of GPA and EGPA although can also be seen in inflammatory bowel disease and other autoimmune diseases [1]. P -ANCA positive results must be followed up by ELISA tests for anti-MPO and anti-PR3 [1]. ANCA measurements are not closely associated with disease activity and should therefore not determine treatment increases or decreases [2]. However treatment withdrawal in patients with a persistently positive ANCA is associated with relapse [2]. Different ANCA patterns can be reported on the same sample in different laboratories due to variations in neutrophil substrate [3].

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Indications

Screening test for small vessel vasculitis. Seen particularly in Granulomatosis with Polyangiitis (GPA), (formerly known as Wegener's granulomatosis), microscopic polyangitis (MPA) and its renal limited variant (pauci-immune crescentic glomerulonephritis) and Eosinophilic Granulomatosis with Polyangiitis (EGPA) (formerly known as Churg-Strauss syndrome).

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Sample Type

2mL Serum (Gel 5mL Yellow tube). Requests from outside Sheffield: Transport at ambient temperature via Royal Mail or Courier.

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Reference Range

Normal result = Negative.

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Turnaround Time

Within 1 day

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Testing Frequency

Daily

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External Notes

Positive results will be followed by specific typing of anti-PR3 and anti-MPO antibodies by ELISA.

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References

Sinclair D, Stevens JM. Role of antineutrophil cytoplasmic antibodies and glomerular basement membrane antibodies in the diagnosis and monitoring of systemic vasculitides. Ann Clin Biochem. 2007. 44(5):432-442.Lapraik C, et al. BSR and BHPR guidelines for the management of adults with ANCA associated vasculitis. Rheumatology. 2007. 46 (10):1615-1616. [Ref 2]Bosch X, Guilabert A and Font J. Antineutrophil cytoplasmic antibodies. Lancet. 2006. 368(9533):404-418.Seo P and Stone J. The Antineutrophil cytoplasmic antibody-associated vasculitides. Am J Med. 2004. 117:39-50.Reumaux D, Duthilleul P, Roos D. Pathogenesis of diseases associated with antineutrophil cytoplasm autoantibodies. Hum Immunol. 2004. 65(1):1-12.Savige J, et al. Addendum to the International Consensus Statement on testing and reporting of antineutrophil cytoplasmic antibodies. Quality control guidelines, comments, and recommendations for testing in other autoimmune diseases. Am. J. Clin. Pathol. 2003. 120(3):312-318. [Ref 1]Pollock W, et al. Immunofluorescent patterns produced by antineutrophil cytoplasmic antibodies (ANCA) vary depending on neutrophil substrate and conjugate. J. Clin. Pathol. 2002. 55:680-683. [Ref 3] Rao J K, et al. The role of antineutrophil cytoplasmic antibody (C-ANCA) testing in the diagnosis of Wegener granulomatosis: a literature review and meta-analysis. Annals of Internal Medicine. 1995. 123(12):925-932.Bossuyt X, et al. Revised 2017 international consensus on testing of ANCAs in granulomatosis with polyangitis and microscopic polyangitis. Nature Reviews Rheumatology. 2017. 13; 683-692.

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See Also

MPO; PR3

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