Lysosomal enzyme activities and low density lipoprotein receptors in circulating mononuclear cells. Effect of insulin therapy in diabetic patients.

Methods for the measurement of the lysosomal enzymes acid cholesterol-ester hydrolase and N-acetyl-beta-glucosaminidase were adapted for use with freshly isolated circulating mononuclear cells. Activities of both these enzymes increased (to 259 and 147% of control values respectively) after 7 days of insulin therapy in diabetic subjects. Low density lipoprotein degradation by freshly isolated mononuclear cells increased simultaneously by 67% (p less than 0.05). The findings in this pilot study suggest [1] that circulating mononuclear cells can be used to evaluate the effect of metabolic changes in vivo on lysosomal enzymes and low density lipoprotein metabolism, and [2] that insulin can stimulate cellular lysosomal enzyme activity.