Brief Report: Simplified Myeloperoxidase Stain Using Benzidine Dihydrochloride

A method is described for demonstrating leukocyte peroxidase activity in which benzidine dihydrochloride is used as the indicator compound instead of the more commonly used but potentially more hazardous benzidine base. The method is highly sensitive and rapid and permits the use of fixed blood smears and organ imprints. The incubation mixture, which incorporates safranin as a counterstain, may be used over and over again, for as long as 6 months. The method is also applicable to fresh frozen tissue sections.