Apolipoprotein C-II is present as a peripheral apoprotein of chylomicrons, very low density lipoproteins (VLDLs), and intermediate density lipoproteins (IDLs). Apolipoprotein C-II activates lipoprotein lipase to hydrolyze triglycerides in the chylomicrons, VLDLs, and IDLs to release free fatty acids for cellular absorption. When the apoprotein is absent, lipoprotein lipase activity is compromised. This results in high triglyceride and chylomicron levels. LDL and HDL levels are abnormally low. The risk of atherosclerosis does not change significantly.