IL-8 and the activation of eosinophils and neutrophils following nasal allergen challenge

Background: A growing body of evidence suggests that proinflammatory cytokines play a role in allergic inflammation by attracting and activating inflammatory cells. In this study, we have investigated the relationship between interleukin-8 (IL-8) in nasal lavage fluid and the local activation of eosinophils and neutrophils following nasal allergen challenge of allergic patients. Methods: Nasal challenges were performed with grass pollen extract in 14 allergic patients and 5 nonallergic controls. Nasal lavage fluid was collected repeatedly for 10 h, and the levels of eosinophil cationic protein (ECP) and myeloperoxidase (MPO) were used as markers of eosinophil and neutrophil activation, respectively. The levels of these molecules were compared with that of IL-g in nasal lavage fluid. Results: Allergen challenge of allergic patients produced a significant late-phase increase in the levels of ECP and MPO. Furthermore, the level of MPO showed a highly significant correlation with the level of IL-8 in lavage fluid (r = 0.8, p < 0.0001), whereas there was no significant relationship between the levels of ECP and IL-8. Conclusion: Interestingly, our findings suggest that both eosinophils and neutrophils are activated following nasal allergen challenge. In addition, our results are consistent with the hypothesis that IL-8 acts as a chemoattractant/activator of neutrophils during the late phase of the allergic inflammation. In contrast, we were not able to demonstrate any significant relationship between the level of IL-8 in lavage fluid and the activation of eosinophils.