Objective: To assess the effect of dexamethasone (Dex) on interleukine-5-induced survival of eosinophils (EOS) in vitro.
Methods: EOS were purified from guinea pigs by Percoll density gradient and incubated for 4 days in the presence of IL-5 with or without Dex. Cell viabilities were determined by staining cells with fluorescein diacetate and propidium iodide.
Results: In the absence of Dex, IL-5 enhanced EOS survival was inhibited in a dosedependent manner. Inhibition was time-dependent and required at least 2 days exposure of EOS to Dex. When EOS were incubated with varying concentrations of IL-5 and 1,000 nmol/l Dex, survival inhibition was reduced at higher concentration of IL-5, and completely abolished by IL-5 1,000 pg/ml.
Conclusions: Dex acts directly on mature EOS to decrease their viabilities, implying the Dex may be important in the treatment of allergic and other inflammatory eosinophilic disorders.