Alpha-naphthyl butyrate esterase (a selective cytochemical monocyte marker).

This paper describes a cytochemical technique for alpha-naphthyl butyrate esterase demonstration in monocytes obtained from peripheral blood of normal subjects, of a patient with reactive monocytosis and of a patient with myelomonocytic leukemia. It utilizes pH 6.1 alpha-naphthyl butyrate as substrate. At this pH value, alpha-naphthyl butyrate is a specific monocyte marker. The cytochemical procedure proposed is simple, rapid and standardized, as it utilizes stable and easily available reagents.