Anti-neutrophil Cytoplasmic Antibodies (ANCA) - Biomarker.org Novel Biomarker Discovery

There are three types of antibodies which target the neutrophils (cANCA, pANCA and atypical ANCA) and can be performed on an urgent basis for patients with suspected autoimmune disorder such as vasculitis and also on a routine basis for follow up of diagnosed patients. Initially screening is performed on ethanol fixed neutrophils at a serum dilution of 1:25. The binding of the antibody is visualised by fluorescent anti-IgG. The positive serum is then subjected to an ELISA technique which is used to quantitative the level of myeloperoxidase (MPO; dominant pANCA autoantigen) and proteinase-3 (PR-3; dominant cANCA ).
Cytoplasmic pattern (cANCA)
Nucleus	Description
	Image: Disease: Antigen:	Granular staining of the cytoplasm of neutrophils. Wegener’s Granulomatosis (90%) A 29 kDa antigen known as proteinase 3 (PR3)

Perinuclear pattern (pANCA)
Nucleus	Description
	Image: Disease: Antigen:	Homogenous perinuclear staining due to an artefact of the fixative. This causes the redistribution of the antigen from the cytoplasm to the perinuclear position. Formalin reverts the pANCA to cANCA. Microscopic Polyangiitis (90%) Myeloperoxidase (MPO)

Atypical ANCA
Nucleus	Description
	Image:	Staining lacks granularity
	Diseases:	Primary Sclerosing cholangitis Autoimmune Hepatitis Primary Biliary Cirrhosis	Rheumatoid Arthritis Ulcerative Colitis Crohn’s Disease
	Antigen:	One of the other antigens may be present e.g. BPI