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The role of eosinophils in the pathogenesis of allergic disorders has been established by several studies. Recently, it has been suggested that second-generation antihistamines, widely used to relieve allergic symptoms, may have anti-inflammatory effects. To assess the possible anti-inflammatory activity of fexofenadine, a selective H1-receptor antagonist, we evaluated its capacity to modulate the expression of adhesion molecules leukocyte function-associated antigen (LFA) 1 and intracellular adhesion molecule (ICAM) 1 on eosinophil surface and to induce apoptosis of eosinophils. To analyze the expression of adhesion molecules, eosinophils from healthy donors were cultured in the presence of interferon γ and tumor necrosis factor a with various concentrations of fexofenadine, incubated with monoclonal antibodies anti-ICAM-1 and LFA-1 and then analyzed by flow cytometry. To evaluate apoptosis of eosinophils, cells stimulated with interleukin-5, in the presence of different concentrations of fexofenadine, have been incubated with a phosphatidylserine-binding protein (annexin V) fluorescein isothiocyanate conjugated and then analyzed by flow cytometry. Apoptosis was evaluated as a percentage of annexin V+ cells. In this study, fexofenadine did not cause any significant changes in the expression of LFA-1 but was shown to be able to inhibit the expression of ICAM-1 at concentrations between 10-3 and 10-4 M. Moreover, concentrations of fexofenadine from 10-3 to 6 × 10-4 M induced a significant increment in the percentage of apoptotic cells. Our findings indicate the possibility of obtaining relevant anti-inflammatory pharmacologic effects, other than antihistamine activity, by fexofenadine, such as inhibition of ICAM-1 expression and induction of eosinophil apoptosis. [ABSTRACT FROM AUTHOR]