Interleukin-8 is a potent mediator of eosinophil chemotaxis through endothelium and epithelium

Interleukin-8 (IL-8), a potent pro-inflammatory cytokine, has been shown to have chemotactic activity for neutrophils, lymphocytes, and basophils. Effects of IL-8 on eosinophil chemotaxis are unresolved. Because eosinophils accumulate at the site of allergic inflammation and may play a role in the pathogenesis of asthma, we investigated the eosinophilotactic capacity of IL-8. We examined the ability of IL-8 to induce human eosinophil migration across 3-microns pore naked filters, and human umbilical vein endothelial cell and human pulmonary type II-like epithelial cell (A549) monolayers cultured on these filters. IL-8 induced similar dose-related eosinophil migration through all three barriers. Kinetic experiments indicated more rapid migration through noncellular barriers but equivalent migration through all barriers by 3 h. Chemotactic/chemokinetic data show that IL-8-induced eosinophil migration is chemotactic. We also determined that the ability of IL-8 to induce transcellular migration was unique in comparison with other cytokines and was not dependent on the use of fresh vs. passaged monolayer cells as barriers. Therefore our data indicate that IL-8 may play a significant role in tissue eosinophilia observed in allergic respiratory diseases.