The role of high density lipoprotein subspecies in the control of lipoprotein metabolism in relation to clinical disorders
In order to examine the role of HDL in the control of lipoprotein metabolism, the levels of HDL subspecies, other lipoproteins, apolipoproteins and fatty acids were measured in four groups of subjects presenting clinical disorders which were possibly related to their lipid profiles. (1) A monoclonal antibody was raised against apolipoprotein A-I allowing the development of an ELISA. (2) In a comparison of 43 angina patients and 61 healthy control subjects, the levels of HDL2, HDL2b and HDL2a were lower in the angina group and this was compensated for by an increase in levels of HDL3b and HDL3c. Plasma triglyceride and VLDL-cholesterol concentrations were higher in the angina group possibly giving rise to the low levels of HDL2 subspecies by their effect on HDL particle conversion. The subspecies HDL2b has been implicated in reverse cholesterol transport. (3) In a study of nine hypertriglyceridaemic subjects and 23 healthy controls there was a lower concentration of HDL2b, HDL2a and LDL-cholesterol and a higher concentration of HDL3b and VLDL-cholesterol in the hypertriglyceridaemic group. This was possibly indicative of reduced LPL activity. The resulting high levels of plasma triglyceride are known to favour the conversion of HDL2 to HDL3. These results suggest that hypertriglyceridaemic patients have a reduced ability to eliminate surplus cholesterol by reverse cholesterol transport and would therefore be at increased risk of atherosclerosis. (4) In a study of 17 violent offenders and 25 control subjects, the HDL subfraction HDL3a was higher in the offenders. The levels of the apolipoproteins E and A-IV were higher in the offender group perhaps having a role in the repair of damaged nervous tissue.