INTERLEUKIN-8 IS A POTENT MEDIATOR OF EOSINOPHIL CHEMOTAXIS THROUGH ENDOTHELIUM AND EPITHELIUM

Interleukin-8 (IL-8), a potent pro-inflammatory cytokine, has been sho wn to have chemotactic activity for neutrophils, lymphocytes, and baso phils. Effects of IL-8 on eosinophil chemotaxis are unresolved. Becaus e eosinophils accumulate at the site of allergic inflammation and may play a role in the pathogenesis of asthma, we investigated the eosinop hilotactic capacity of IL-8. We examined the ability of IL-8 to induce human eosinophil migration across 3-mu m pore naked filters, and huma n umbilical vein endothelial cell and human pulmonary type II-like epi thelial 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 noncellula r barriers but equivalent migration through all barriers by 3 h. Chemo tactic/chemokinetic data show that IL-8-induced eosinophil migration i s chemotactic. We also determined that the ability of IL-8 to induce t ranscellular migration was unique in comparison with other cytokines a nd was not dependent on the use of fresh vs. passaged monolayer cells as barriers. Therefore our data indicate that IL-8 may play a signific ant role in tissue eosinophilia observed in allergic respiratory disea ses.