Effects of ragweed and Th-2 cytokines on the secretion of IL-8 in human airway epithelial cells

Ragweed-induced asthma is a very common pulmonary disease. An important part of asthma is a large increase in in ammatory cells, including neutrophils and eosinophils, in ragweed-sensitilized subjects. In this study, we determined if ragweed treatment could induce the release of interleukin-8 (IL-8) by human airway epithelial cells. We found that ragweed induces a substantial increase of the secretion of IL-8 from A549 cells in a dose- and time-dependent manner. Th- 2 cytokines, IL-4 and IL-13, partially inhibited the ragweed-induced secretion of IL-8. Our results suggest that airway epithelial cells may be one of the cell sources that provide IL-8 during ragweed-induced asthma. The results also indicate that IL-4 and IL-13 may exert inhibitory effects on IL-8 secretion by airway epithelium.