Myeloperoxidase (MPO) is a specific polymorphonuclear enzyme that is most abundantly expressed in neutrophil granulocytes. It functions in the oxygen-dependent killing of microorganisms and is released from primary granules of neutrophils during acute inflammation. MPO is encoded by the MPO gene, which is about 11kb and composed of 11 introns and 12 exons, located in chromosome 17 (q12-24). The mature 150 kDa MPO protein is a dimer consisting of two 15kDA light chains and two heavy chains in variable degrees of glycosylation.
MPO is related both to inflammation and oxidative stress. It is a sensitive predictor for myocardial infarction in patients presenting chest pain. Studies ahve indicated that MPO is causally linked to atherosclerosis. Moreover, a combination test of MPO and CRP (C-reactive protein) provides added benefit for risk prediction of cardiovascular mortality than by simply measuring CRP alone. This assay utilizes a specific monoclonal antibody to capture MPO in test samples to ensure that only myeloperoxidase is detected.