Strain dependence of airway hyperresponsiveness reflects differences in eosinophil localization in the lung

Different strains of mice exhibit different degrees of airway hyperresponsi veness after sensitization to and airway challenge with ovalbumin. Antibody responses in BALB/c mice far exceeded those in C57BL/6 mice; in contrast, although responsiveness to methacholine was much higher in the BALB/c mice, the number of eosinophils in the bronchoalveolar lavage fluid was higher i n C57BL/6 animals. Sensitized and challenged BALB/c mice developed increase s in lung resistance and decreases in dynamic compliance after methacholine or 5-hydroxytryptamine inhalation. C57BL/6 mice only exhibited significant levels of responsiveness when dynamic compliance was monitored in response to inhaled 5-hydroxytryptamine. Eosinophils accumulated in the peribronchi al and peripheral lung tissue in BALB/c mice but were distributed diffusely in the peripheral lung tissue of C57BL/6 mice. Thus, in addition to differ ences in antibody responses and cholinergic agonist reactivity, differences in the responses of large and small airways may reflect the selective dist ribution of eosinophils in lung tissue.