Antimyeloperoxidase (MPO) Antibodies

Antibodies against myeloperoxidase (MPO) are referred to as p-ANCA subtype, since they form a perinuclear fluorescence pattern. This ANCA-fluorescent (antineutrophil cytoplasmic antibodies) subtype includes other antibodies such as antibodies against lactoferrin, cathepsin G or elastase. However, in at least 60% of p-ANCA reactivity cases, the main antigen is MPO. Anti-MPO antibodies are primarily considered an important indicator for progressing nephritis; they are largely present in patients with severe renal impairment. They are also important for diagnosing Churg-Strauss syndrome and microscopic polyangiitis. The presence or absence of antibodies against MPO and PR3 in combination with the positivity of antinuclear antibodies may be regarded as a differentiating marker between ANCA-associated vasculitis and SLE-induced vasculitis.