Cytochemical demonstration of esterases in peripheral blood leukocytes

Cytochemical methods for alpha naphthyl acetate esterase and chloroacetate esterase have been used to identify human monocytes and granulocytes. In this study, a standard procedure for staining alpha naphthyl acetate and chloroacetate esterase activities was modified by extending the range of pH of the incubation mixture and the duration of staining and was applied to cat, dog, goat, guinea pig, hamster, human, pig, rabbit, rat, and sheep leukocytes. The results for both enzymes showed (1) incubation time and pH had discrete effects on staining and (2) species differences for in vitro conditions to demonstrate esterase activity were pronounced.