Antineutrophil Cytoplasmic Antibody (ANCA)-Associated Vasculitis (AAV) is an autoimmune vasculitis that mainly includes Granulomatosis with Polyangiitis (GPA), Microscopic Polyangiitis (MPA), and Eosinophilic Granulomatosis with Polyangiitis (EGPA).
The antinuclear antibody (ANA) is a defining feature of autoimmune connective tissue disease. ANAs are a class of antibodies that bind to cellular components in the nucleus, including proteins, DNA, RNA, and nucleic acid-protein complexes. ANA identification has been the foundation of diagnosis for autoimmune connective tissue disease, including systemic lupus erythematosus (SLE), Sjogren's syndrome, and polymyositis/dermatomyositis.
Antibodies (Abs) to soluble liver antigen/liver pancreas (anti-SLA/LP) are considered markers of worse prognosis and outcome in patients with autoimmune hepatitis (AIH).
Anti-MDA-5 antibody are specifically associated with dermatomyositis, and define a skin-lung syndrome with a frequent severe disease course. Anti-TIF1-γ is also associated with dermatomyositis but its presence is frequently predictive of a cancer association whereas anti-MI2 is associated with the classical dermatomyositis. Two specific antibodies, anti-SRP and anti-HMGCR, are observed in patients with immune-mediated necrotizing myopathies and may be very useful to distinguish acquired myopathies from dystrophic muscular diseases in case of a slow onset and to allow the initiation of effective therapy.