IL-10 is necessary for the expression of airway hyperresponsiveness but not pulmonary inflammation after allergic sensitization

Cytokines play an important role in modulating inflammatory responses and, as a result, airway tone. IL-10 is a regulatory cytokine that has been sugg ested for treatment of asthma because of its immunosuppressive and anti-inf lammatory properties. In contrast to these suggestions, we demonstrate in a model of allergic sensitization that mice deficient in IL-10 (IL-10-/-) de velop a pulmonary inflammatory response but fail to exhibit airway hyperres ponsiveness in both in vitro and in vivo assessments of lung function. Reco nstitution of these deficient mice with the IL-10 gene fully restores devel opment of airway hyperresponsiveness comparable to control mice, These resu lts identify an important role of IL-10, downstream of the inflammatory cas cade, in regulating the tone of the airways after allergic sensitization an d challenge.