Role of the Th2 cytokines in the development of allergen-induced airway inflammation and hyperresponsiveness

Increased production of interleukin (IL)-4 and IL-5 by T-helper cells may be pivotal for the induction and regulation of allergic diseases. We have studied the role of IL-4 and IL-5 in the development of eosinophilic airway inflammation (Al) and airway hyperresponsiveness (AHR) in a mouse model of allergen-induced bronchial asthma. Utilizing different modes of sensitization, we delineated the importance of IL-5-mediated eosinophilic airway infiltration for the development of in vitro and in vivo AHR and demonstrated the inhibition of airway inflammation and AHR by anti-IL-5 antibody treatment. Studies in IL-4- and IL-5 deficient mice revealed the importance of both cytokines for the induction of Al and AHR independently from the production of allergen-specific IgE, and indicated these cytokines as potential targets in novel approaches in the treatment of asthma.