Inhibition of human eosinophil chemotaxis in vitro by the anti-allergic agent emedastine difumarate

Emedastine difumarate (emedastine), an anti-allergic agent with antihistaminic properties, was studied for its effect on human eosinophil chemotaxis induced by platelet activating factor (PAF). Peripheral blood eosinophils (98% purity) were obtained from healthy donors and chemotaxis assay were performed in microchemotaxis chambers. Emedastine showed a significant inhibitory effect on 10(-6) M PAF-induced eosinophil chemotaxis, in dose dependent fashion, at concentrations from 10(-6) to 10(-8) M. Conversely, no inhibitory effect was observed on human neutrophil chemotaxis. Pretreatment of eosinophils with Pyrilamine did not affect PAF-induced eosinophil chemotaxis. Thus emedastine appears to possess a potent and selective inhibitory effect on eosinophils chemotaxis, an action which is probably unrelated to its anti-histamine properties.