Acid phosphatase heterogeneity in horse neutrophil and eosinophil leukocytes.

Two distinct groups of acid phosphatase containing granules were characterized in neutrophils, each group displaying different multiple forms of the enzyme. The heavy granule acid phosphatase showed a lysosomal location. A second lighter group of particles contained a thermolabile, thiol-dependent acid p-nitrophenyl and alpha-naphtylphosphatase, an enzyme clearly different from lysosomal acid phosphatase. Acid phosphatase activity from eosinophil leukocytes appeared to be totally associated with the typical eosinophil granules. On mechanical disruption of these particles, an acid phosphatase was released which differed in substrate and inhibitor specificity, in electrophoretic pattern, and in thermosensitivity, from the remaining matrix-bound enzyme.