A rapid, sensitive myeloperoxidase stain using 4-chloro-1-naphthol.

The substitution of 4-chloro-1-naphthol for benzidine-containing compounds used in the myeloperoxidase stain for distinguishing granulocytes from lymphoid blood elements is described. 4-Chloro-1-naphthol is an acceptable substitute for benzidine compounds, which are considered to be carcinogenic. The feasibility of using this method on peripheral blood and bone-marrow films is discussed.