Effect of antigen provocation of IL-5 transgenic mice on eosinophil mobilization and bronchial hyperresponsiveness

We investigated whether allergen-induced eosinophil recruitment into mouse airways modifies the in vivo bronchopulmonary responses to standard agonists, an adaptation of a technique described for larger animals. Swiss, CBA, and IL-5 transgenic mice were immunized with ovalbumin and challenged intranasally after 14 days. Immunization alone was followed by increased eosinophil counts in bone marrow and blood, whereas antigenic challenge induced eosinophil infiltration in lungs and bronchoalveolar lavage fluid, which was suppressed by dexamethasone. Despite the high eosinophil counts, no bronchopulmonary hyperreactivity to methacholine or serotonin was detected 3 to 96 hoots after antigenic provocation. Our results demonstrate that immunization augments the production of eosinophils by mice, which is further increased by antigenic challenge, brit that eosinophil overproduction and lung infiltration, per se, are not sufficient to induce bronchopulmonary hyperreactivity, even in constitutively hypereosinophilic IL-5 transgenic mice.