Effect of eicosapentaenoic and docosahexaenoic acid on natural killer cell activity in human peripheral blood lymphocytes.

The effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on natural killer (NK) cell activity in human peripheral blood lymphocytes were studied. The direct addition of trieicosapentaenoyl-glycerol (EPA-TG) or tridocosahexaenoylglycerol (DHA-TG) emulsion to a cytotoxicity assay system significantly suppressed NK cell activity. The addition of lipoxygenase inhibitor AA861 also inhibited NK cell activity. The inhibition was proportional to the concentration of EPA-TG emulsion. DHA-TG emulsion, or AA861. The presence of both EPA-TG emulsion or DHA-TG emulsion and AA861 at the same time led to a greater inhibitory effect on NK cell activity than when these emulsions were used separately. The inhibitory effect caused by these lipids or lipoxygenase blockade could not be reversed by adding back exogenous leukotrienes to the assay system. Preincubation of effector cells with EPA-TG or DHA-TG emulsion resulted in a significant inhibition of their NK cell activity. NK cell activity of human lymphocytes was markedly decreased after the infusion of EPA-TG emulsion into healthy volunteers. Thus, in vivo use of EPA-TG or DHA-TG emulsion may influence immune reactivity of the host, although the mechanism has not yet been elucidated.