Relationship between high density lipoproteins and the rate of in vitro serum cholesterol esterification

The rate of in vitro esterification of serum cholesterol and the concentrations of serum high density lipoprotein cholesterol (HDL-C) were measured in 18 women and 9 men, 74--95 years of age. Subjects in this age group can have HDL-C levels below accepted limits of normal. The subjects were divided into two groups, one with HDL-C less than 40 mg/dl and the other with HDL-C 40 mg/dl or higher. The rate of in vitro serum cholesterol esterification in the former group was 2.00 n. moles/ml/min, significantly higher (p less than 0.02) than 1.62 n. moles/ml/min present in the latter group. There was no correlation between the cholesterol esterification and a protein (s), which can produce an immune gamma globulin that completely inhibits in vitro serum cholesterol esterification. These findings are discussed with reference to the putative relationships between HDL-C and atherosclerosis.