Extracellular release of free fatty acids by rat T lymphocytes is stimulus-dependent and is affected by dietary lipid manipulation

[H-3]-Arachidonic acid-labelled rat T lymphocytes released radioactivity ex tracellularly when stimulated by the calcium ionophore A23187 or by monoclo nal antibodies to some cell surface structures (CD2, CD5, CD11a, CD18, CD54 . T-cell receptor) but not to others (CD49d, CD62L); release was greater wi th the calcium ionophore. Almost all of the radioactivity released from ant i-CD2-stimulated lymphocytes was recovered in the free fatty acid fraction, whereas only about 50 per cent of that released after A23187 stimulation w as recovered in this fraction. A23187 stimulation resulted in release of ar achidonic acid from a variety of phospholipids (phosphatidylinositol, phosp hatidylcholine and perhaps phosphatidylethanolamine), while the monoclonal antibody stimulation released arachidonic acid from phosphatidylinositol an d perhaps phosphatidylcholine. Unstimulated lymphocytes released a range of fatty acids extracellularly, with palmitic acid accounting for 35-40 per c ent and arachidonic acid for 5 per cent of released fatty acid. Stimulation of lymphocytes with either anti-CD2 or A23187 increased total fatty acid r elease 1.5- to 1.8-fold. In both cases palmitic acid remained the most pred ominant fatty acid released but the contribution of arachidonic acid increa sed. The type of lipid fed to the rats significantly influenced the amount and type of fatty acid released. Fish oil feeding significantly reduced ext racellular fatty acid release by stimulated lymphocytes, Copyright (C) 2000 John Wiley & Sons, Ltd.