ANCA Associated Diseases/Vasculitis

ANCA-associated vasculitides include granulomatosis with polyangiitis (GPA) formerly known as Wegener’s granulomatosis, microscopic polyangiitis (MPA) and eosinophilic granulomatosis with polyangiitis (EPA) formerly known as Churg-Strauss syndrome (CSS).

They are characterised by an interaction of anti-neutrophil cytoplasm autoantibodies (ANCA) with neutrophils which may be important in initiating vascular injury. Vasculitis is the inflammation of vessel walls and can lead to fibrosis, necrosis or thrombosis. This can result in damage to the body’s organs. Some other examples of vasculitis would be Kawasaki’s disease and Giant cell arteritis, with smaller vessels being affected by GPA and MPA.

Myeloperoxidase (MPO) has been identified as the main target antigen in MPA associated
ANCAs and proteinase 3 (PR3) in GPA. MPO antibodies produce a perinuclear (pANCA) pattern and PR3 antibodies a granular cytoplasmic (cANCA) pattern when performing IIF.

EIAs using MPO and PR3 as antigens are generally the most commonly performed assays alongside IIF. Lactoferrin, bactericidal/permeability increasing protein (BPI) and cathepsin G antibodies have also been reported to possibly play a role in vasculitis. These could be potential markers but further research is needed to determine their diagnostic value.

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