PAF-induced eosinophil chemotaxis increases during an asthmatic attack and is inhibited by prednisolone in vivo and in vitro.

We investigated platelet-activating factor (PAF)-induced migration in eosinophils obtained from asthmatic patients who were treated with or without intravenous prednisolone. The migration of asthmatic eosinophils in remission and during an attack was significantly greater than that in healthy volunteers. The migration of asthmatic eosinophils exposed to prednisolone in vivo and in vitro was significantly inhibited, compared to asthmatic eosinophils not exposed to prednisolone. These findings suggest that an intracellular factor causes asthmatic eosinophils to migrate, and that prednisolone inhibits PAF-induced eosinophil migration.