Dexamethasone does not modulate eosinophil adhesion to endothelial cells

Background: Glucocorticoids are representative agents in the anti-inflammat ory treatment of allergic airway diseases. Although they reduce the number of tissue eosinophils, its exact mechanism has not been completely establis hed. Objective: The present study was undertaken to evaluate whether dexame thasone modulates the adhesive property of eosinophils. The effect on the e xpression of endothelial adhesion molecules was also evaluated. Methods: Bl ood eosinophils from healthy subjects were incubated in the presence or abs ence of 0.1-1 muM of dexamethasone for 6 h at 37 degreesC. Eosinophil chemo taxis and adhesion to paraformaldehyde-fixed human pulmonary vascular endot helial cells (HPMEC) were then examined. The effects of dexamethasone on th e expression of VCAM-1 and ICAM-1 on HPMEC were examined by cell ELISA. Res ults: 1 muM dexamethasone significantly inhibited the chemotactic response of eosinophils to 1 muM formyl-methionyl-leucyl-phenylalanine (FMLP). On th e other hand, dexamethasone did not modify either the spontaneous or FMLP-s timulated adhesion of eosinophils to resting HPMEC. Similarly, dexamethason e did not alter either the spontaneous adhesion of eosinophils to or the ex pression of VCAM-1 or ICAM-1 on HPMEC stimulated with IL-4 + TNF-alpha. Con clusion: Dexamethasone does not modify the adhesive property of eosinophils or the expression of adhesion molecules on endothelial cells. Thus, it is unlikely that glucocorticoids directly modulate the adhesive interaction be tween eosinophils and endothelial cells. Copyright (C) 2001 S. Karger AG, B asel.