Mediator (β-hex) release in agonist-stimulated eosinophils and effects of dexamethasone.
(A) Freshly purified eosinophils (2 × 105 cells) were stimulated using IFN-γ, C5a/CB, and IL-3/IL-5/GM-CSF for 10 minutes, and β-hex was measured in cell-free supernatants. The effect of dexamethasone on agonist-induced mediator release was examined by preincubating cells with dexamethasone (10−6) for 60 minutes. A similar trend of release was observed in 6 separate donors. The first column shows spontaneous release of β-hex from eosinophils, the second and third columns show IFN-γ–induced release and dexamethasone effect, the fourth and fifth columns represent the C5a/CB-induced release and dexamethasone effect, and the sixth and seventh columns show the IL-3/IL-5/GM-CSF–induced release and dexamethasone effect. (B) Freshly purified eosinophils (2 × 106 cells) were stimulated using a different concentration of IFN-γ for 10 minutes, and RANTES was measured in cell-free supernatants. A similar trend of release was observed in 4 separate donors. (C) Freshly purified eosinophils (2 × 106 cells) were stimulated using a different concentration of IFN-γ for 10 minutes, and EPO was measured in cell-free supernatants. A similar trend of release was observed in 4 separate donors. The Student t test was used to analyze the results. In all experiments, given values represent averages of triplicate measurements. *The statistical significance of dexamethasone inhibition of mediator release; error bars represent the mean and SEM of measurements (*P < .01).
