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The effects of in vitro additions of between 10 and 100 µM n-6 and n-3 polyunsaturated fatty acids were examined on the proliferation of stimulated T lymphocytes in culture. For both phytohemagglutinin-induced human blood lymphocytes and concanavalin-A-induced rat splenic lymphocytes, the largest inhibitory effects were obtained with 22:4 n-6 and 22:6 n-3, and to a lesser extent with 20:5 n-3. Arachidonic acid 20:4 n-6, the main eicosanoid presursor, was not inhibitory, it even stimulated rat lymphocyte proliferation. Acetylsalicylic acid stimulated both human and rat lymphocyte proliferation. The effects of moderate decreases in the dietary n-6/n-3 ratio by either linseed oil or fish oil maximum eicosapentaenoic acid (MaxEPA) were determined on rat lymphocyte proliferation and natural killer (NK) cell activity in vitro. Dietary changes did not affect mitogen-induced lymphocyte proliferation in vitro, but proliferation of unstimulated lymphocytes was significantly lowered (4-fold) with the n-3-enriched diets. Dietary fish oil but not linseed oil significantly increased the NK cell activity of rat splenic lymphocytes. The n-3-enriched diets, especially the fish oil diets, reduced the stimulatory effect of in vitro added acetylsalicylic acid (aspirin) on lymphocyte proliferation.

The purpose of this study was to evaluate the effects of different doses of dietary γ-linolenic acid (GLA) on the tissue phospholipid fatty acid composition and the synthesis of eicosanoids in growing rats. The supplementation with different oils rich in GLA (borage oil, evening primrose oil, or Spirulina oil) and poor in n-3 polyunsaturated fatty acids or biomass of Spirulina results in a significant dose-related increase of GLA and dihomo-GLA in liver, erythrocyte, and aorta phospholipids in rats fed during 6 weeks different levels of GLA. The arachidonic acid (AA)/dihomo-GLA ratios decreased with increasing intake of dietary GLA, but the AA proportions remained stable. The dietary administration of GLA increased the in vitro production by the aorta of prostaglandin E_1· derived from dihomo-GLA, but did not significantly influence the production of prostaglandin E₂ derived from AA by the aorta and the thromboxane B₂ level in serum.

Summary. Mother-fetus transfer and uptake of essential fatty acids by the rat fetus.Transfer through the placenta and uptake of 14 C linoleic and arachidonic acids by the fetus were investigated in the 20-day old rat fetus. 14 C-labelled blood originating from pregnant rats fed 14 C methyl-linoleate was perfused in situ during 13 min. into the placentofetal system.