Antineutrophil cytoplasmic antibodies (ANCA): diagnostic utility and potential role in the pathogenesis of vasculitis

Antineutrophil cytoplasmic antibodies (ANCA) are a heterogeneous group of circulating antibodies directed toward the cytoplasmic constituents of neutrophils and monocytes. ANCA have been described in various diseases including idiopathic systemic vasculitides, connective tissue diseases, inflammatory bowel diseases, autoimmune liver diseases, infectious diseases, and some drugs. ANCA recognize different target antigens such as proteinase 3 (PR3-ANCA), myeloperoxidase (MPO-ANCA), cathepsin G, lactoferrin, bactericidal/permeability-increasing protein (BPI), and some others. However, only PR3-ANCA and MPO-ANCA are closely associated with systemic vasculitides, in particular Wegener's granulomatosis, microscopic polyangiitis and its renal limited manifestation, and Churg-Strauss syndrome. Both in vitro and in vivo experimental data strongly support a pathogenic role for ANCA in vasculitis and glomerulonephritis.