Macrophages transfer [C-14]-labelled fatty acids to pancreatic islets in culture

Macrophages are able to produce, export, and transfer fatty acids to lympho cytes in culture. The purpose of this study was to examine if labelled fatt y acids could be transferred from macrophages to pancreatic islets in co-cu lture. We found that after 3 h of co-culture the transfer of fatty acids to pancreatic islets was: arachidonic >> oleic > linoleic = palmitic. Substan tial amounts of the transferred fatty acids were found in the phospholipid fraction; 87.6% for arachidonic, 59.9% for oleic, 53.1% for palmitic, and 3 6.9% fur linoleic acids. The remaining radioactivity was distributed among the other lipid fractions analysed (namely polar lipids, cholesterol, fatty acids, triacylglycerol and cholesterol eater), varying with the fatty acid used. For linoleic acid, a significant: proportion (63.1%) was almost equa lly distributed in these lipid fractions. Also, it was observed that transf er of fatty acids from macrophages to pancreatic islets is time-dependent u p to 24 h, being constant and linear with time for palmitic acid and remain ing constant after 12 h for oleic acid. These results lead us to postulate that in addition to the serum, circulating monocytes may also be a source o f fatty acids to pancreatic islets, mainly arachidonic acid. Copyright (C) 2001 John Wiley & Sons, Ltd.