A histochemical procedure for localizing and evaluating leukocyte alkaline phosphatase activity in smears of blood and marrow.

By LEONARD S. KAPLOW T HE RESULTS of previous studies’8 on the histochemical localization of alkaline phosphatase activity in cells of blood and bomie marrow have been varied and contradictory. All such studies, except that of Vercauteren,8 were based on the Gomori-Takamutsu procedure.” ‘#{176}Numerous investigators”9 have shown that this procedure may produce false staimiing of nuclei and other structures, particularly with long incubation times. Furthermore, the fixation methods used in these studies did not always adequately preserve cytologic detail. The presemit communication describes a rapid arid simple procedure for demomistratimig alkaline phosphatase activity in cells of blood and marrow, in which a new fixative procedure and the azo dye staining method are used.2023 A “scoring” method is described whereby intracellular alkaline phosphatase activity in blood smears from different individuals may be compared amid evaluated. Brodell and Swisher7 reported a technic for deriving “leukocyte alkaline phosphatase indices.” They described their method as being “based upon microscopic grading from 0 to 4 of the depth of staining of 100 successive leukocytes.” Cells were selected for grading on smears prepared from separated leukocytes obtaimied by differential centrifugatiomi. They recommelided the use of a phase microscope. In deriving their indices, these authors coumited leukocytes of all types. Simice alkalimie phosphatase activity appears limited to neutrophils only, their figures probably did not accurately reflect the degree of activity of the phosphatase-containing leukocytes. The applicatiomi of the staining amid scorimig methods herein described offers