Transport of apolipoproteins A-I and A-II by human thoracic duct lymph

• Published in: The Journal of clinical investigation Vol. 67; no. 3; pp. 857 - 866
• Main Authors: Anderson, D W, Schaefer, E J, Bronzert, T J, Lindgren, F T, Forte, T, Starzl, T E, Niblack, G D, Zech, L A, Brewer, Jr, H B
• Format: Journal Article
• Language: English
• Published: United States 01.03.1981
• Subjects: Apolipoproteins - metabolism; Biological Transport; Cholesterol - blood; Cholesterol - metabolism; Humans; Lipoproteins, HDL - blood; Lipoproteins, HDL - metabolism; Lymph - metabolism; Molecular Weight; Triglycerides - blood; Triglycerides - metabolism
• ISSN: 0021-9738
• DOI: 10.1172/JCI110103

The daily transport of human plasma apolipoproteins A-I and A-II, triglyceride, and total cholesterol from the thoracic duct lymph into plasma was measured in two subjects before and three subjects after renal transplantation. Lymph triglyceride transport was approximately 83% of the daily ingested fat loads, whereas lymph cholesterol transport was consistently greater than the amount of daily ingested cholesterol. Lymph apolipoprotein transport significantly (P < 0.05) exceeded the predicted apolipoprotein synthesis rate by an average of 659+/-578 mg/d for apolipoprotein A-I and 109+/-59 mg/d for apolipoprotein A-II among the five subjects. It is estimated that 22-77% (apolipoprotein A-I) and 28-82% (apolipoprotein A-II) of daily total body apolipoprotein synthesis takes place in the intestine. Lymph high density lipoprotein particles are mostly high density lipoprotein(2b) and high density lipoprotein(2a) and have a greater overall relative triglyceride content and a smaller relative cholesteryl ester content when compared with homologous plasma high density lipoproteins. The major quantity of both lymph apolipoprotein A-I (81+/-8%) and apolipoprotein A-II (90+/-11%) was found within high density lipoproteins with almost all of the remainder found in chylomicrons and very low density lipoproteins. The combined results are consistent with a major contribution of the intestine to total body synthesis of apolipoprotein A-I and apolipoprotein A-II. An important role of lymph in returning filtered apolipoprotein to plasma in association with high density lipoproteins is proposed. Accompanying the return of filtered apolipoprotein to the plasma is a probable transformation, both in size and composition, of at least some of the lymph high density lipoprotein(2b) and high density lipoprotein(2a) particles into high density lipoprotein(3).