Abstract
Alkaline phosphatase activity of neutrophils was estimated histochemically with special reference to various types of hemolytic disorders. Enzyme activity tended to be lower than normal in all but one of the cases studied. Leukocytes incubated for one hour at 37°C in plasma obtained from a patient with paroxysmal nocturnal hemoglobinuria and from a patient with congenital spherocytosis showed a decrease in enzyme activity. When leukocytes were incubated in normal plasma containing bovine hemoglobin, enzyme activity also decreased. Plasma obtained from patients with hyperbilirubinemia caused by bile duct obstruction did not affect enzyme activity in vitro at all. It was concluded from these observations that the low enzyme activity seen in various hemolytic disorders was due to the inhibitory effect of hemoglobin in plasma and not due to indirect bilirubin. Differences in enzyme activity in these hemolytic states were considered to be due to differences in plasma hemoglobin concentration.
