Light and Electron Microscopic Localization of Acid Phosphatase Activity in Human Eosinophils

Abstract

Acid phosphatase activity was cytochemically demonstrated in human eosinophile granules either as descrete cytoplasmic particles or as ring-shaped structures as seen in the light microscope (Gomori method, pH5). Buffy coat from human heparinized blood was fixed in glutaraldehyde, incubated for acid phosphatase activity and examined under the electron microscope. This combined study confirmed the light microscope findings and localized acid phosphatase activity to the peripheral noncrystalline portion of the eosinophile granule. The central crystal of this granule exhibited no enzyme activity. The presence of acid phosphatase activity within this single membrane bound cytoplasmic organelle places it into the category of structures called lysosomes.