The influence of epinastine hydrochloride (EP) on eosinophil survival was examined by an in vitro cell culture technique. Nasal epithelial cells (NECs) were stimulated with 25 ng/ml TNF-alpha in the presence of EP (10 to 30 ng/ml). After 24 h, the culture supernatants were obtained and used as conditioned media of NECs (CM). Eosinophils (1 x 10(3) cells/ml) prepared from healthy human peripheral blood were incubated with 25% CM and eosinophil survival was assessed by trypan blue dye exclusion test 48 h later. CM prepared from NEC cultures pre-treated with TNF-alpha and EP caused a decrease in eosinophil survival as compared with that from NEC cells pre-treated with TNF-alpha alone. The minimum concentration of EP that caused a significant decrease in eosinophil survival was 25 ng/ml. The addition of EP into eosinophil cultures did not cause inhibition of eosinophil survival, which was prolonged by stimulation with granulocyte-macrophage colony-stimulating factor (GM-CSF), even when 40 ng/ml EP was added to cell cultures. We then examined the levels of GM-CSF in CM by ELISA. Treatment of NECs with EP at more than 25 ng/ml, reduced the ability of NECs to produce GM-CSF in response to TNF-alpha stimulation. These results may suggest that EP suppresses eosinophil survival through the suppression of GM-CSF production from NECs induced by inflammatory stimulation and that this suppressive effect contributes, in part, to the therapeutic mode of action of EP on allergic diseases.