Background: Allergic inflammation is regulated by the local production and release of several cytokines.
Objectives: This study was designed to assess the changes in mRNA cytokine-positive cells after allergen provocation and to compare these cytokines with tissue eosinophilia as a marker of allergic inflammation.
Methods: A grass pollen allergen provocation study was conducted in autumn, out of the hay fever season. Nasal mucosal biopsy specimens were taken before provocation and 1 hour, 24 hours, and 1 week after allergen provocation. Eosinophils and mRNA-positive cells (in situ hybridization for IL-2, IL-3, IL-4, IL-5, IL-6, IL-8, IL-10, IL-13, IFN-gamma, RANTES, and TNF-alpha) were assessed in the biopsy specimens.
Results: After allergen provocation, an increase in cell number was found for eosinophils and cells expressing mRNA for the chemokines IL-8 and RANTES and for the TH2 cytokines IL-10 and IL-13. Significant correlations were found between eosinophils and RANTES and eosinophils and IFN-gamma in the early phase and between eosinophils and IL-5 and eosinophils and RANTES in the late phase. The increase in eosinophils and IL-10 and IL-13 mRNA-positive cells could still be observed 1 week after allergen provocation.
Conclusions: Nasal allergen provocation induced significant tissue eosinophilia and a significant increase in IL-8, IL-13, and RANTES mRNA-positive cells. A significant increase in eosinophils and IL-10 and IL-13 mRNA-positive cells compared with baseline can still be observed 1 week after a single allergen provocation.