Increased glutathione peroxidase activity in human blood mononuclear cells upon in vitro incubation with n-3 fatty acids.

Fish oil-enriched diets have been shown to increase the n-3 polyunsaturated fatty acid (PUFA) content of cell membranes, in vivo, and to simultaneously enhance the glutathione peroxidase (glutathione: H2O2 oxidoreductase, EC 1.11.1.9) (GSH-Px) activity of platelets and erythrocytes both in animals and humans. The present study aimed to determine whether in vitro enrichment of human peripheral blood mononuclear cells (PBMC) with either eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) might have similar influence on the GSH-Px activity of these cells. Pretreatment of human PBMC for a short period of time (90 min) with 5 microM of either EPA or DHA was sufficient to induce a significant enrichment of cellular phospholipids in the corresponding fatty acid. This was accompanied by an increased GSH-Px activity of these cells. This stimulatory effect proved to be specific of n-3 fatty acids since it was not observed with saturated, monounsaturated or n-6 polyunsaturated fatty acids. Neither EPA nor DHA had a direct influence on the GSH-Px activity of PBMC in cell-free preparations. Both fatty acids had no influence on the distribution of total proteins between the cytosolic and the particulate compartments. EPA did not significantly alter the GSH-Px kinetic behavior thus suggesting an increased expression of the enzyme. In addition, DHA slightly but significantly decreased the proliferative response of PBMC to the mitogenic stimulation by Con A whereas EPA only tended to do so.