Native, human eosinophil peroxidase is a secreted hemoprotein that catalyzes oxidations of various substrates by hydrogen peroxide. Together with other leukocyte-derived enzymes, such as Myeloperoxidase, EPO plays an important role in the pathogenesis of asthma by mediating oxidative events that lead to the production of ROS (reactive oxygen species) and RNS (reactive nitrogen species).