Inhibition of Leukocyte Acid Phosphatase by Heparin

Low concentrations of heparin (<1 unit/mI) inhibit by 80 % the activity of leukocyte acid phosphatase. Leukocyte /3-giucuronidase is less sensitive to hepa-rin, and alkaline phosphatase and lysozyme are un-affected. The possible inhibitory effects of heparin should be considered in all measurements of leuko-cyte enzymatic activities. For some time we have been concerned with the role of alkaline and acid phosphatases (orthophosphoric monoest-en phosphohydrolases, EC 3.1.3.1 and EC 3.1.3.2, respec-tively) in polymorphonuclear leukocytes, particularly as regards variation in disease states and factors that might regulate the activity within the cell (1-4). Here we dem-onstrate that relatively small concentrations of heparin profoundly inhibit leukocyte acid phosphatase, but hav