PURIFIED DIETARY N-3 POLYUNSATURATED FATTY-ACIDS ALTER DIACYLGLYCEROLMASS AND MOLECULAR-SPECIES COMPOSITION IN CONCANAVALIN A-STIMULATED MURINE SPLENOCYTES

A low-dose, short-term dietary supplementation with highly purified (n - 3) fatty acid ethyl esters was studied in mice to determine the eff ect on splenic cell membrane diacylglycerol mass and composition. Mice were fed diets containing either 3% safflower oil (SAF) ethyl esters, 2% SAF plus 1% eicosapentaenoic acid ethyl ester (EPA), or 2% SAF plu s 1% docosahexaenoic acid ethyl ester (DHA). Following a 10-day feedin g period, pathogen-free mice were sacrificed and splenic cells isolate d and stimulated with concanavalin A (Con A) at 10 mu g/ml. After 0 mi n (basal), 5 min, and 180 min, 1,2-diacyl, 1-O-alkyl-2-acyl, and 1-O-a lkenyl-2-acyl-sn-glycerol subclasses were isolated and quantitated by HPLC. Diacylglycerol (DAG) was found to be the major diradylglycerol ( DG) component in murine splenocytes. DHA-fed mice had significantly (P < 0.05) higher levels of DAG at all stimulation time points relative to EPA and SAF animals. Significant effects (P < 0.05) of diet, time, and a diet x time interaction (P < 0.05) were noted for various DAG mo lecular species. In general, a significantly higher (n - 3) polyunsatu rated fatty acid (PUFA) content in the EPA and DHA groups, and a signi ficantly higher (n - 6) PUFA content in the SAF group was noted. 18:0- 22:5(n - 3), 18:1-22:5(n - 3) and 16:1-20:5(n - 3) species were presen t only in EPA and DHA-DAG, confirming the incorporation of (n - 3) fat ty acids into splenocyte DAG. The data indicate that the molecular spe cies composition of murine splenocyte DAG is significantly modulated b y low-dose, short-term EPA and DHA feeding. In addition, substitution of SAF with DHA results in an increase in DAG mass. These alterations could potentially influence signal transduction pathways regulating ly mphocyte function.