Anti-Neutrophil Cytoplasmic Antibodies (ANCA) MPO, PR3 and ANCA IIF

Anti-neutrophil cytoplasmic antibodies (ANCA) are directed against cytoplasmic constituents of polymorphonuclear leukocytes and monocytes. Many patients with primary small vessel vasculitis, e.g. granulomatous with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatous with polyangiitis (EGPA) harbour ANCA directed against either PR3 (proteinase 3) or MPO (myeloperoxidase). ANCA are found at a much lower frequency in patients with limited disease.

The 2017 International Consensus (Bossuyt, X. et al. Nat Rev Rheumatol 13, 683–692 (2017)) recommend that screening for ANCA-associated vasculitides be performed using a solid phase quantitative assay.

MPO and PR3 assays are performed by fluoroenzymeimmunoassay (Immunocap) on Phadia. The laboratory also performs ANCA by indirect immunofluorescence (IIF) on ethanol-fixed neutrophils. All new positive MPO and PR3 patients are confirmed by an MPO/PR3/GBM immunoblot.

Monitoring ANCA disease (MPO/PR3)
Glomerulonephritis, especially rapidly progressing glomerulonephritis
Pulmonary haemorrhage, especially pulmonary renal syndrome
Acute pulmonary-renal syndrome
Cutaneous vasculitis with systemic features
Multiple lung nodules
Chronic destructive disease of the upper airways
Long-standing sinusitis or otitis
Granulomatous nasopharyngeal lesions
Subglottic tracheal stenosis
Mononeuritis multiplex, or other peripheral neuropathy
Retro-orbital mass
Scleritis

ANCA MPO = <3.5 IU/mL
ANCA PR3 = <2 IU/Ml
ANCA IIF = Negative
Ranges were derived by manufacturer and verified in house

ANCA by IIF is currently unaccredited due to a recent change in platform.