Apolipoprotein A-1 (APO A) and Apolipoprotein B (APO B)

Written by: Solaris Diagnostics

Apolipoprotein A-I (apo A-I) is the major structural and functional protein component of high-density lipoprotein (HDL), or good cholesterol in plasma. It accounts for approximately 70% of HDL. Apo A-I activates lecithin cholesterol acyltransferase (LCAT) which catalyzes the esterification of cholesterol. The resulting esterified cholesterol can then be transported to the liver, metabolized, and excreted. Person with atherosclerotic vascular changes frequently exhibit decreased level of Apo A-I. A decreased level of Apo A-1 level is a risk factor for atherosclerotic processes.

Similarly, Apolipoprotein B (APO B) is the main protein component of chylomicrons, Low-density lipoprotein (LDL), and very low-density lipoprotein (VLDL), intermediate density lipoprotein (IDL), and lipoprotein (a). It accounts for approximately 95% of the total protein content of LDL. Apo B is necessary for the reaction with LDL receptors in the liver and on cell walls and is thus involved in transporting cholesterol from the liver to the vessel cell. Elevated level of Apo B is frequently found in patients with atherosclerotic vascular changes and are a risk factor for atherosclerosis. It is noted that several studies have shown that the assay of Apo A-I and Apo B is helpful in assessing the risk of atherosclerosis and has greater prognostic power than the sole determination of HDL and LDL.

Solaris diagnostics laboratory uses state of art nephelometric analyzer that offers broad range of protein assay. Proteins contained in human body fluids form immune complexes with specific antibodies. These complexes scatter a beam of light passed through the sample. The intensity of the scattered light is proportional to the concentration of the relevant protein in the sample. The result is evaluated by comparison with a standard of known concentration. Solaris Diagnostics can provide the results for Apo A-I and Apo B results within 24 hours from the time the sample is received in the laboratory.



Cochran BJ, Ong KL, Manandhar B, Rye KA. APOA1: a Protein with Multiple Therapeutic Functions. Curr Atheroscler Rep. 2021 Feb 16;23(3):11. doi: 10.1007/s11883-021-00906-7. PMID: 33591433.

Devaraj S, Semaan JR, Jialal I. Biochemistry, Apolipoprotein B. 2022 Sep 12. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan–. PMID: 30844166.

Walldius G, Jungner I. The apoB/apoA-I ratio: a strong, new risk factor for cardiovascular disease and a target for lipid-lowering therapy–a review of the evidence. J Intern Med. 2006 May;259(5):493-519. doi: 10.1111/j.1365-2796.2006.01643.x. PMID: 16629855.

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