Volume 90, Issue 6, December (2003), pp. 1071-1080 © The Author 2003
doi:10.1079/BJN2003996

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The effect of feeding structured triacylglycerols enriched in eicosapentaenoic or docosahexaenoic acids on murine splenocyte fatty acid composition and leucocyte phagocytosis

Samantha Kew¹, Edward S. Gibbons¹, Frank Thies^1,2, Gerald P. McNeill^3,4, Paul T. Quinlan^3,5, Philip C. Calder^1
1Institute of Human Nutrition, University of Southampton, Southampton, SO16 7PX, , UK
²Department of Medicine and Therapeutics, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, , UK
³Unilever Research Colworth Laboratory, Sharnbrook, Bedford, MK44 1LQ, , UK
⁴Loders Croklaan NA, Channahon, IL, 60410, , USA
⁵Unilever Health Institute, Unilever Research Vlaardingen, 3130 AC Vlaardingen, The Netherlands

 (Received 10 April 2003–Revised 16 July 2003–Accepted 7 August 2003)

The effects of altering the type of n-3 polyunsaturated fatty acid (PUFA) in the mouse diet on the ability of monocytes and neutrophils to perform phagocytosis were investigated. Male weanling mice were fed for 7 d on one of nine diets which contained 178 g lipid/kg and which differed in the type of n-3 PUFA and in the position of these in dietary triacylglycerol (TAG). The control diet contained 4·4 g α-linolenic acid/100 g total fatty acids. In the other diets, eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) replaced a proportion (50 or 100 %) of the α-linolenic acid, and were in the sn-2 or the sn-1(3) position of dietary TAG. There were significant increases in the content of n-3 PUFA in spleen-cell phospholipids when EPA or DHA was fed. These increases were largely independent of the position of EPA or DHA in dietary TAG except when EPA was fed at the highest level, when the incorporation was greater when it was fed in the sn-2 than in the sn-1(3) position. There was no significant effect of dietary DHA on monocyte or neutrophil phagocytic activity. Dietary EPA dose-dependently decreased the number of monocytes and neutrophils performing phagocytosis. However, when EPA was fed in the sn-2 position, the ability of active monocytes or neutrophils to engulf bacteria was increased in a dose-dependent fashion. This did not occur when EPA was fed in the sn-1(3) position. Thus, there appears to be an influence of the position of EPA, but not of DHA, in dietary TAG on its incorporation into cell phospholipids and on the activity of phagocytic cells.

Keywords:
Polyunsaturated fatty acids, Fish oil, Phagocytosis, Immune function, Monocytes

Abbreviations:
ALNA, α-linolenic acid, ARA, arachidonic acid, DHA, docosahexaenoic acid, DPA, docosapentaenoic acid, EPA, eicosapentaenoic acid, MFI, median fluorescence intensity, NEFA, non-esterified fatty acid, PL, phospholipid, PUFA, polyunsaturated fatty acid, TAG, triacylglycerol