Volume 91, Issue 6, June (2004), pp. 893-903 © The Author 2004
doi:10.1079/BJN20041131

The influence of different combinations of γ-linolenic acid, stearidonic acid and EPA on immune function in healthy young male subjects

Elizabeth A. Miles¹, Tapati Banerjee¹, Maaike M. B. W. Dooper², Laura M'Rabet², Yvo M. F. Graus² and Philip C. Calder^1
1Institute of Human Nutrition, School of Medicine, University of Southampton, Bassett Crescent East, Southampton, SO16 7PX, UK
²Numico Research BV, P. O. Box 7005, Wageningen, NL-6700, The Netherlands

 (Received 21 August 2003–Revised 11 December 2003–Accepted 17 February 2004)

To determine the effects of EPA, stearidonic acid (STA) or γ-linolenic acid (GLA) on immune outcomes, healthy male subjects consumed one of seven oil blends for 12 weeks. EPA consumption increased the EPA content of peripheral blood mononuclear cells (PBMC). Consumption of GLA (2·0 g/d) in the absence of STA or EPA increased di-homo-GLA content in PBMC. Neither STA nor its derivative 20 : 4n-3 appeared in PBMC when STA (<1·0 g/d) was consumed. However, STA (1·0 g/d), in combination with GLA (0·9 g/d), increased the proportion of EPA in PBMC. None of the treatments altered neutrophil or monocyte phagocytosis or respiratory burst, production of inflammatory cytokines by monocytes, T lymphocyte proliferation or the delayed-type hypersensitivity response. Production of cytokines by T lymphocytes increased in all groups, with no differences among them. The proportion of lymphocytes that were natural killer cells decreased significantly in subjects receiving 2·0 g EPA or GLA/d. There were no other effects on lymphocyte sub-populations. Plasma IgE concentration decreased in most groups, but not in the control group. Plasma IgG₂ concentration increased in the EPA group. Thus, EPA or GLA at a dose of 2·0 g/d have little effect on key functions of neutrophils, monocytes and T lymphocytes, although at this dose these fatty acids decrease the number of natural killer cells. At this dose EPA increases IgG₂ concentrations. STA can increase immune cell EPA status, but at 1·0 g/d does not affect human immune function.

Keywords:
Cytokine, Immunoglobulin, Phagocytosis, Respiratory burst

Abbreviations:
ALA, α-linolenic acid, BO, borage oil, con A, concanavalin A, DGLA, di-homo-γ-linolenic acid, DHA, docosahexaenoic acid, DTH, delayed-type hypersensitivity, EO, echium oil, GLA, γ-linolenic acid, ICAM, intercellular adhesion molecule, IFN, interferon, LPS, lipopolysaccharide, MFI, median fluorescence intensity, PBMC, peripheral blood mononuclear cell, SI, stimulation index, STA, stearidonic acid