Deletion of IL-4Rα signaling on B cells limits hyperresponsiveness depending on antigen load

BACKGROUND: B cells play an important role in allergies through secretion of IgE. IL-4 receptor α (IL-4Rα) is key in allergic asthma and regulates type 2 cytokine production, IgE secretion, and airway hyperresponsiveness. IL-4 activation of B cells is essential for class switching and contributes to the induction of B effector 2 (Be2) cells. The role of Be2 cells and signaling via IL-4Rα in B cells is not clearly defined. OBJECTIVE: We sought to find out whether IL-4Rα–responsive B cells or Be2 function was essential in experimental allergic asthma. METHODS: Mice lacking IL-4Rα on B cells (mb1(cre)IL-4Rα(−/lox)) or littermate controls (IL-4Rα(−/lox)) and mice lacking IL-4 or IL-4/IL-13 on B cells were sensitized and challenged with high-dose house dust mite (>10 μg) or with low-dose house dust mite (<3 μg). We also adoptively transferred naive IL-4Rα(−/lox) or IL-4Rα(−/−) B cells into μMT(−/−) mice a day before sensitization or a day before challenge. We analyzed lung inflammation, cellular infiltrate, and airway hyperresponsiveness. RESULTS: We found that IL-4Rα signaling on B cells was important for optimal T(H)2 allergic immune responses mainly when the load of antigen is limited. IL-4Rα signaling on B cells was essential for germinal centers and in the effector phase of allergic responses. Be2 cells were essential in airway hyperresponsiveness, but not in other parameters. CONCLUSIONS: IL-4Rα signaling on B cells is deleterious in allergic asthma because it is required for optimal T(H)2 responses, Be2 function, germinal center formation, and T follicular helper cells, especially when the load of the antigen is limiting.