The Clinical Application of a Modified Azo-Dye Technic for the Determination of Alkaline Phosphatase Activity in Neutrophils

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THE phosphatases are a group of enzymes that release orthophosphoric acid from many phosphate esters and, to a lesser extent, participate in the reverse reaction. These enzymes differ in their optimal pH and, on this basis, they may be classified as either acid or alkaline phosphatases. In 1939, Gomori1 and Takamatsu2 independently described a method for the cytochemical demonstration of alkaline phosphatase. Since that time the distribution of alkaline phosphatase in the cells of the hematopoietic system has been the subject of much study. In 1944, Menten, Junge, and Green3 described an azo-dye method for the demonstration of the enzyme. The basic reactions in the technic are the release of naphthol from an alpha-naphthyl phosphate substrate, and its combination with a diazotized amine to form an azo dye. This dye forms a colored precipitate at the site of action of the alkaline phosphatase within the cells.

Reports4–8 differ both as to the types of cell that contain alkaline phosphatase and as to the distribution of the enzyme within the individual cells. Nevertheless, most authors agree that it is the alteration in enzyme content of the segmented neutrophils which offers the most useful diagnostic information. In chronic granulocytic leukemia the enzyme activity of the segmented neutrophils has been shown4–14 to be greatly reduced or absent, whereas in other forms of granulocytosis this activity is frequently increased. Polycythemia vera,15 myelofibrosis,13,14 Hodgkin's disease15 and pregnancy16 are also associated with increased neutrophil alkaline phosphatase.

The purpose of this paper is to present a modified . . .



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