Effect of high polyunsaturated fat diets on the composition of B cell and T cell membrane lipids

Abstract Mice were fed semipurified diets differing in polyunsaturated to saturated fatty acid ratio to provide two diet fats, either high or low in linoleic acid. The levels of linoleic acid and other major fatty acid constituents present in B and T cell membrane phosphatidylcholine and phosphatidylethanolamine fractions were determined. To determine the rate at which membrane phosphatidylcholine and phosphatidylethanol-amine fatty acid composition of B and T cell changes in response to diet treatment, young animals at 6 weeks of age were fed for 1, 4 or 6 week periods. To examine the degree to which response to diet differed between young and old mice of different strains and between B and T cells, membrane phospholipid fatty acid composition for mice was compared at 98 weeks of age with young individuals fed the diets for the same treatment period. Lower levels of linoleic acid in T cell membranes of older animals were observed when compared with membranes of young animals fed diet treatments for the same period. Change in 18:2(6) content of T cell phosphatidylcholine as a result of feeding both diets for periods of 1, 4 or 6 weeks was observed and appeared to be maximal by 4 to 6 weeks of feeding. The degree of change in membrane 18:2(6) content was greatest in young animals. Strain specific differences between membrane composition of B and T cells were observed, with effect of diet being most pronounced on the content of 16:0 and 20:4(6) in phosphatidylcholine and on the content of 18:0, 18:2(6) and 20:4(6) in phosphatidylethanolamine. Results suggest that aging alters the controls over incorporation of diet fatty acids into T and B cell membranes and the endogenous metabolism of essential fatty acids in a manner that may be peculiar to specific sub-populations of cells.