Development of Lung Eosinophilic Inflammation by the Infusion of IL-5-Producing T Cell Clones

To delineate the critical role of T cells on asthma, we tested whether eosinophilic inflammation of the bronchial mucosa is induced by transfer of IL-5-producing T cell clones, in the absence of antigen-specific immunoglobulins (IgE, A and G). Ovalbumin-specific T cell clone, FI5, that produced IL-5 upon challenge with relevant antigen was established. Eosinophilic inflammation of the lung occurred when unprimed mice were transferred with FI5 and challenged by the inhaled antigen. Eosinophil infiltration was completely suppressed by the administration of anti-IL-5 neutralizing antibody, indicating the essential role of IL-5. We concluded that the existence of IL-5-producing helper T cells is sufficient for the development of airway eosinophilic inflammation.