Reacts with myeloperoxidase (MPO), a hemoprotein of 140 kDa, composed of two heavy subunits of 52 kDa and two light chains of 15 kDa. MPO is stored in primary azurophilic granules of neutrophils and plays a major role in the bactericidal activity of neutrophils during phagocytosis. It catalyzes the generation of hypochlorous acid, a powerful oxidant. 1B10 antibody detects MPO in neutrophils, monocytes and HL-60 cells. This reagent is suitable for immunohistochemical staining of acetone-fixed, frozen tissue section, or formalin-fixed, paraffin-embedded tissue sections with TUF pretreatment, or zinc-fixed, paraffin-embedded tissue sections with no pretreatment.