ALLERGIC AIRWAY SENSITIZATION INDUCES T-CELL ACTIVATION BUT NOT AIRWAY HYPERRESPONSIVENESS IN B-CELL-DEFICIENT MICE

B cells play an important role in the allergic response by producing a llergen-specific Igs as well as by serving as antigen-presenting cells . We studied the involvement of B cells in the development of response s in a murine model of allergic airway sensitization, Normal and B cel l-deficient (mu Mt(-/-)) B10.BR mice were sensitized via the airways t o ovalbumin; Ig production, cytokine elaboration from local lymph node cells, development of airway hyperresponsiveness, and histological ch anges in the airways were evaluated. Both strains of mice had increase d production of T helper 2-like cytokines and developed an accumulatio n of eosinophils in the bronchial tissue after airway sensitization. H owever, only wild-type mice produced allergen-specific antibodies and exhibited altered airway function. B cell-deficient mice reconstituted with anti-ovalbumin IgE during the course of sensitization developed increases in airway responsiveness, These results indicated that neith er B cells nor IgE were necessary for the induction of a T helper 2-ty pe cytokine response or eosinophil infiltration of the airways after a llergic sensitization but that IgE was required as a second signal for the development of airway hyperresponsiveness in this model of airway sensitization.