Modulation of eosinophil chemotactic activities to leukotriene B₄ by n-3 polyunsaturated fatty acids

Eosinophil accumulation induced by leukotriene B₄ appears to be involved in the pathogenesis of allergic diseases. We evaluated the effects of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on chemotaxis to leukotriene B₄ in guinea pig peritoneal eosinophils. Guinea pigs that were sensitized to polymyxin B were administered an intraperitoneal injection of polymyxin B (1 mg/animal) alone or combined with DHA (15 or 50 mg/kg, i.p.), EPA (50 or 100 mg/kg, i.p.), or with linoleic acid (LA) (100 mg/kg, i.p.). Forty hours later, eosinophils were obtained from the intraperitoneal ravage fluid and purified. The chemotactic and chemokinetic responses of eosinophils to leukotriene 3, were measured using a 96-well microchemotaxis chamber. DHA significantly decreased the chemotactic and chemokinetic responses of eosinophils in a dose-dependent fashion. A higher dose of EPA also significantly inhibited both of those responses, whereas LA had no effect. Our results suggested a possible mechanism for the improvement of allergic diseases by dietary supplementation with n-3 PUFA.