Demonstration of intact intracellular cholesterol esterification and normal low-density lipoprotein pathway in fibroblasts from a patient with lecithin:cholesterol acyltransferase deficiency.

There was a 6-46-fold increase in intracellular cholesterol esterification in response to 25-hydroxycholesterol and low-density lipoproteins in normal and lecithin:cholesterol acyltransferase-deficient fibroblasts. Uptake and degradation of 125I-labelled low-density lipoproteins were similar in the two cell lines. Low-density lipoproteins caused a doubling of the mass of cholesteryl ester in the mutant cells. These findings indicate that: (a) acyl-CoA:cholesterol acyltransferase exhibits normal activity in mutant cells; (b) lecithin:cholesterol acyltransferase and acyl-CoA:cholesterol acyltransferase are different enzymes and are probably not products of the same gene; (c) the low-density lipoprotein-pathway is intact in fibroblasts from a patient with lecithin:cholesterol acyltransferase deficiency; (d) acyl-CoA:cholesterol acyltransferase is probably responsible for the small amount of cholesteryl ester found in plasma from patients with lecithin:cholesterol acyltransferase deficiency.