Which lipoprotein is most directly associated with delivering cholesterol to tissues and promoting plaque buildup?

• A. HDL
• B. IDL
• C. VLDL
• D. LDL

Answer: (D)

Lipoproteins transport lipids in the blood, and the particle that delivers cholesterol directly to most tissues is low-density lipoprotein. LDL carries cholesterol with apolipoprotein B-100 that binds LDL receptors on cells, allowing uptake of cholesterol for membrane synthesis and other uses. When LDL levels are high or the particle becomes oxidized, macrophages take up the cholesterol, forming foam cells and initiating inflammatory processes that lead to fatty streaks and atherosclerotic plaque buildup. This direct delivery and pro-atherogenic cascade make LDL the lipoprotein most closely linked to plaque formation. In contrast, HDL removes cholesterol from tissues for return to the liver, VLDL primarily ferries triglycerides from the liver to tissues, and IDL is an intermediate particle transitioning toward LDL.