Ragweed antigen causes interleukin-8 production in sensitized dog trachea

Antigen challenge in allergic subjects and in sensitized animals causes recruitment of neutrophils as well as eosinophils into the airways. In this study, we asked whether interleukin-8 (IL-8) is involved in the recruitment of neutrophils into the airways after antigen challenge. We administered ragweed antigen to an isolated, superfused tracheal segment of ragweed-sensitized dogs. Local tracheal instillation of the antigen caused an increase in IL-8 concentration and increases in both the number of recruited neutrophils and myeloperoxidase activity (one indicator of neutrophil activation in the recruited cells). The increase in IL-8 concentration was observed earlier than both the neutrophil recruitment and the increase in myeloperoxidase activity in the tracheal superfusate. Superfusate removed from the trachea 8 h after antigen challenge showed marked neutrophil chemotactic activity in a microchemotaxis chamber, and this activity was inhibited (mean, 75.6%) by a blocking antibody to dog IL-8. We conclude that ragweed antigen causes neutrophil recruitment into the airways at least in part because of IL-8 production.