Dose-response effects of dietary gamma-linolenic acid-enriched oils on human polymorphonuclear-neutrophil biosynthesis of leukotriene B4.

The dose-dependent effect of dietary supplemented gamma-linolenic acid (GLA, 18:3n-6)-enriched borage oil (Bor) and black-currant oil on the ability of calcium ionophore-activated human polymorphonuclear neutrophils (PMN) to generate leukotriene B4 (LTB4) was investigated in adult healthy human volunteers. Significant (P less than 0.05) elevation of dihomo-gamma-linolenic acid (DGLA, 20:3n-6), an elongation product of GLA, was revealed in PMN phospholipids after ingestion of either 0.48 or 1.5 g GLA-enriched oil/d. This elevation of DGLA in the PMN phospholipids paralleled the decreased capacity of calcium ionophore-activated PMN to generate LTB4. Although the inhibition of LTB4 was greater with the ingestion of 1.5 g GLA-enriched BOR/d, it was not significantly different from the ingestion of 0.48 g/d. Taken together, dietary ingestion of GLA-fortified oils does modulate PMN generation of proinflammatory LTB4.