title: Triacylglycerol metabolism by lymphocytes and the effect of triacylglycerols on lymphocyte proliferation.
abstract: This study investigates the ability of lymphocytes to utilize fatty acids originating from triacylglycerols and the effect of triacylglycerols upon mitogen-stimulated lymphocyte proliferation. Lymphocytes isolated from rat lymph nodes, spleen, thymus and lymphatic duct had a lipoprotein lipase activity of approx. 10 units/mg of protein, indicating that the fatty acids of circulating triacylglycerols are accessible to these cells. In culture lymph node lymphocytes hydrolysed triacylglycerols added to the medium as emulsions. Both non-esterified fatty acids and free glycerol appeared in the cell culture medium, but their concentrations indicated that a high proportion of each (65-90% of fatty acids and 60-80% of glycerol) was taken up by the cells. The incorporation and fate of triacylglycerol-fatty acids was studied by culturing the cells in the presence of tri[3H]oleoylglycerol or tri[14C]inoleoylglycerol. Both fatty acids were incorporated into lymphocyte lipids in a time-dependent manner; linoleic acid was incorporated at a significantly greater rate than oleic acid. The majority of oleic acid (greater than 70%) was incorporated into cellular triacylglycerol, while less than 10% was incorporated into phospholipids. In contrast, linoleic acid incorporation into cellular triacylglycerol never exceeded 25%, while up to 45% was incorporated into phospholipids. Triacylglycerols containing polyunsaturated fatty acids inhibited concanavalin A-stimulated lymphocyte proliferation in a concentration- and time-dependent manner; triacylglycerols containing saturated fatty acids or oleic acid were not inhibitory. Such direct effects of certain triacylglycerols on lymphocyte function may explain why some clinical trials of polyunsaturated fatty acid-rich diets have been successful in improving the condition of patients suffering from inflammatory diseases.
authors.affiliation: Department of Biochemistry, University of Oxford, UK.
authors.forename: P C
authors.initials: PC
authors.lastname: Calder
authors.forename: P
authors.initials: P
authors.lastname: Yaqoob
authors.forename: E A
authors.initials: EA
authors.lastname: Newsholme
mesh_terms: D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004655:Emulsions; D005227:Fatty Acids / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D007700:Kinetics; D019787:Linoleic Acid; D008041:Linoleic Acids / Q000378:metabolism; D008071:Lipoprotein Lipase / Q000378:metabolism; D008213:Lymphocyte Activation / Q000187:drug effects*; D008214:Lymphocytes / Q000187:drug effects / Q000502:physiology*; D008297:Male; D019301:Oleic Acid; D009829:Oleic Acids / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014280:Triglycerides / Q000378:metabolism* / Q000494:pharmacology*
chemical_list: D004655:Emulsions; D005227:Fatty Acids; D008041:Linoleic Acids; D009829:Oleic Acids; D014280:Triglycerides; D019301:Oleic Acid; D019787:Linoleic Acid; D008071:Lipoprotein Lipase; D005990:Glycerol