Abstract
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 < 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 < 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.