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During the preclinical study of new therapeutic modality, we evaluate whether the treatment can reverse the established asthma phenotypes in animal model. How-ever, few have reported on the long term persistence of asthma phenotypes upon re-challenge with allergen (secondary challenge) in animal model. We evaluated the persistence of asthma phenotypes by secondary challenge at different times in previously challenged murine asthma model. BALB/c mice sensitized by intraperi-toneal injections of 20 g of ovalbumin and 1 mg of alum on days 1 and 14 were challenged initially by the inhalation of 1% ovalbumin for 30 min on days 21, 22, and 23. Each group of mice was rechallenged at 5, 7, 9, or 12 weeks after the initial challenge. Airway hyperresponsiveness, BAL fluid, airway histology and serum ovalbumin-specific IgE level were evaluated. Airway eosinophilia, airway inflammation and serum ovalbumin-specific IgE production persisted upon sec-ondary allergen challenges at least 12 weeks after the initial challenge. However, airway hyperresponsiveness persisted only until mice were rechallenged 7 weeks after the initial challenge. Airway inflammation and allergen specific IgE production may persist longer than airway hyperresponsiveness in a mouse asthma model of secondary allergen challenge.
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