Myeloperoxidase deficiency Myeloperoxidase deficiency is a hereditary deficiency of the enzyme, which causes a mild
immune deficiency against certain
pathogens.
Atherosclerosis and heart disease Myeloperoxidase is known to contribute to
atherosclerosis and diseases related to it, including
coronary artery disease. MPO oxidizes
LDL cholesterol, and as a result, the
LDL receptor in liver cells becomes unable to bind to LDL and remove it from the blood stream. However, in its oxidized state, LDL can still contribute to
foam cell formation and other atherosclerotic processes. Thus, elevated levels of MPO are a risk factor for atherosclerosis.
Medical tests An initial 2003 study suggested that MPO could serve as a sensitive predictor for
myocardial infarction in patients presenting with
chest pain. Since then, there have been over 100 published studies documenting the utility of MPO testing. The 2010 Heslop et al. study reported that measuring both MPO and CRP (C-reactive protein; a general and cardiac-related marker of inflammation) provided added benefit for risk prediction than just measuring CRP alone.
Immunohistochemical staining for myeloperoxidase used to be administered in the diagnosis of
acute myeloid leukemia to demonstrate that the leukemic cells were derived from the
myeloid lineage. Myeloperoxidase staining is still important in the diagnosis of
myeloid sarcoma, contrasting with the negative staining of
lymphomas, which can otherwise have a similar appearance. In the case of screening patients for vasculitis,
flow cytometric assays have demonstrated comparable sensitivity to
immunofluorescence tests, with the additional benefit of simultaneous detection of multiple autoantibodies relevant to vasculitis. Nonetheless, this method still requires further testing.
Inhibitors Azide has been used traditionally as an MPO inhibitor, but 4-aminobenzoic acid hydrazide (4-ABH) is a more specific inhibitor of MPO. == See also ==