Objective: To investigate whether challenge with increasing allergen doses could differently affect allergen-induced airway hyperresponsiveness (AHR) and inflammatory cell accumulation in mouse model of asthma, providing an experimental model to investigate their relationship.
Material and methods: AHR and accumulation of inflammatory cells in bronchoalveolar lavage fluid (BALF) and into the lungs were compared in ovalbumin-sensitized mice that were challenged intranasally with 2.5, 10, 25 or 100 microg of ovalbumin/mouse.
Results: Both AHR and inflammatory cell accumulation were proportional to the ovalbumin dose used for challenge. However, in group challenged with 10 microg of ovalbumin airway inflammation was present, although allergen-induced AHR was not detected. Additional analysis indicated that neither mucous hyperproduction nor eosinophil degranulation could be correlated to presence of AHR in this model, whereas concentration of interleukin (IL)-13 in BALF was increased only in those groups in which AHR was present.
Conclusions: Altogether, intranasal challenge of mice with increasing allergen doses could serve as a suitable experimental system for investigation of mechanisms by which airway inflammation leads to allergen-induced AHR. Our initial findings are in line with previous reports that dissociate AHR from amount of eosinophil accumulation and imply the role of IL-13 in this process.