The clinical features and pathology of vasculitis associated with anti-myeloperoxidase autoantibodies.

Autoantibodies to myeloperoxidase (MPO) are associated with the autoimmune disease, systemic vasculitis, in humans. This results in severe inflammation and microscopic necrosis of multiple organs, especially the kidneys, leading to renal failure and death. The discovery of MPO autoantibodies has permitted the development of new diagnostic tests allowing earlier diagnosis and more effective therapy. Furthermore these antibodies are directly implicated in tissue injury by binding to MPO on the neutrophil cell membrane and stimulating neutrophil activation and degranulation. The causes for the breakdown in tolerance to MPO are not known although rare cases are drug-induced and remit on drug withdrawal. An understanding of the biology of MPO and its involvement in the pathogenesis of vasculitis is of importance in understanding the pathogenesis of vasculitis and the development of newer therapies.