PURIFIED DIETARY N-3 POLYUNSATURATED FATTY-ACIDS ALTER DIACYLGLYCEROL MASS 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 effect 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 plus 1% docosahexaenoic acid ethyl ester (DHA). Following a 10-day feeding period, pathogen-free mice were sacrificed and splenic cells isolated and stimulated with concanavalin A (Con A) at 10 mu g/ml. After 0 min (basal), 5 min, and 180 min, 1,2-diacyl, 1-O-alkyl-2-acyl, and 1-O-alkenyl-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 molecular species. In general, a significantly higher (n - 3) polyunsaturated fatty acid (PUFA) content in the EPA and DHA groups, and a significantly 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 present only in EPA and DHA-DAG, confirming the incorporation of (n - 3) fatty acids into splenocyte DAG. The data indicate that the molecular species composition of murine splenocyte DAG is significantly modulated by 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 lymphocyte function.