Interleukin-5 and interleukin-8 in relation to eosinophils and neutrophilsin nasal fluids from school children with seasonal allergic rhinitis

The objectives of this study were to measure interleukins 5 and 8 (IL-5 and IL-8) in relation to eosinophils and neutrophils, in nasal lavage fluids f rom 60 school children with allergic rhinitis, and to determine the influen ce of treatment with a topical steroid (budesonide) on the levels of the tw o cytokines, Highly sensitive enzyme immunoassays were used to analyze IL-5 and IL-8. IL-5 levels and relative eosinophil counts in nasal lavage fluid increased significantly in patients with allergic rhinitis during the poll en season, compared with values obtained before the start of the season, an d decreased significantly after treatment with budesonide. By contrast, no significant changes in IL-8 or neutrophils were found during the pollen sea son, nor did they decrease following treatment. In the untreated patients, IL-5 levels correlated significantly with eosinophil counts but not with ne utrophil counts, whereas IL-8 levels correlated with neutrophil counts but not with eosinophil counts. After budesonide treatment, the correlation bet ween IL-8 and neutrophils remained, and a correlation between IL-8 and eosi nophils emerged. These findings support the concepts that IL-5 has a key ro le in regulating eosinophils and that IL-8 is important for the regulation of neutrophils. Whereas IL-5 and relative eosinophil counts are profoundly affected by topical steroid treatment, IL-8 and neutrophils are not demonst rably affected by such treatment. It is possible that neutrophils, through the release of IL-8, could be chemotactic for eosinophils in steroid-treate d patients.