ApoBcontaining

ApoB-containing lipoproteins are a class of lipoprotein particles that carry apolipoprotein B (ApoB) as their primary structural protein. The main members in humans are chylomicrons, very low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), low-density lipoprotein (LDL), and lipoprotein(a) (Lp(a)). Chylomicrons originate in the intestine and transport dietary triglycerides; VLDL and its remnants carry endogenous triglycerides produced by the liver; LDL delivers cholesterol to tissues; IDL is a transitional remnant between VLDL and LDL; Lp(a) is an LDL-like particle that carries an additional protein, apolipoprotein(a), linked to ApoB-100.

Structure and role of ApoB: Each particle typically contains one molecule of ApoB—ApoB-48 in chylomicrons and ApoB-100 in hepatic lipoproteins. This makes ApoB a useful marker of particle number, not just cholesterol content. ApoB-containing lipoproteins transport triglycerides and cholesterol through the bloodstream and deliver lipids to peripheral tissues or the liver for processing.

Clinical significance: Levels of ApoB-containing lipoproteins are closely associated with atherosclerotic cardiovascular disease risk. Because one particle generally carries one ApoB molecule, ApoB measurement or non-HDL cholesterol (the sum of cholesterol in these particles) provides an estimate of circulating atherogenic particle burden, sometimes more informative than LDL cholesterol alone. Lp(a) adds further risk independent of LDL, with its impact influenced by genetic factors.

Measurement and management: Direct ApoB testing is available and used in some guidelines to assess risk and guide therapy. Lipid-lowering strategies such as statins, PCSK9 inhibitors, ezetimibe, and lifestyle changes aim to reduce ApoB-containing particle burden. In certain individuals, elevated ApoB may prompt more aggressive risk reduction.