Inhibition of neutral cholesteryl ester hydrolase by a naturally occurring cytosolic protein in macrophages.

The soluble fraction from a number of macrophage cell lines has been shown to contain a protein(s) that inhibits neutral cholesteryl ester hydrolase. The inhibition is dependent on the concentration of soluble protein used, and the efficiency of the inhibitor can be influenced by the inclusion of oleate and an inhibitor of ACAT. It is suggested that the presence of this material indicates that the macrophage contains a means of negatively controlling the activity of the hydrolytic phase of the cholesterol/cholesteryl ester cycle.