Ethyl eicosapentaenoate restored the immunosuppression in mice fed fat-free diet.

The effects of eicosapentaenoic acid (EPA) on the humoral immune response in fat free diet-fed (FF) mice were studied. The lowered anti-SRBC PFC activity of ICR male FF mice was restored in a dose-dependent manner when EPA was administered orally at doses of 60-360 mg/kg/day for 20 days. In in vitro experiments, EPA similarly enhanced anti-SRBC PFC activity but did not affect the response against lipopolysaccharide. Furthermore, EPA did not cause any substantial effect on T suppressor cell activity induced by Concanavalin A in vitro. On the other hand, T helper cell activity induced by keyhole limpet hemocyanin was augmented. From these results, it is suggestive that EPA caused immunopotentiation to FF mice at least partially by an enhancement of T helper cell activities.