Test Details: Myeloperoxydase (MPO) is an intracellular enzymatic protein expressed at an early stage in the differentiation of the myeloid cell line. MPO is synthesized primarily during the formation of promyelocytes, the stage during which azurophile granules, or primary granules, are formed. The enzyme myeloperoxidase (MPO) is the most specific marker of myeloid lineage, thus presence of MPO in leukaemic blast cells can be done by conventional cytochemistry and immunological methods using a monoclonal antibody anti-MPO (CLB-MPO1) which helps in diagnosing most cases of acute leukaemia of myeloid lineage.