HDL concentrations vary reciprocally with plasma triacylglycerol concentrations and directly with the activity of lipoprotein lipase. This may be due to surplus surface constituents, eg, phospholipid and apo A-I, being released during hydrolysis of chylomicrons and VLDL and contributing toward the formation of preβ-HDL and discoidal HDL. HDL2 concentrations are inversely related to the incidence of atherosclerosis, possibly because they reflect the efficiency of reverse cholesterol transport. HDLc (HDL1) is found in the blood of diet-induced hypercholesterolemic animals. It is rich in cholesterol, and its sole apolipoprotein is apo E. It appears that all plasma lipoproteins are interrelated components of one or more metabolic cycles that together are responsible for the complex process of plasma lipid transport. Reference:  HARPERS ILLUSTRATED BIOCHEMISTRY30th ed Page no 259