Antigen-induced eosinophil recruitment into the airways of sensitized mice is mediated by CD4+ T cells and their cytokines, especially IL-5. In this study, we found that the antigen-induced airway eosinophilia was diminished in Stat5a-deficient (Stat5a−/−) mice and Stat5b-deficient (Stat5b−/−) mice. We also found that antigen-induced CD4+ T-cell infiltration and IL-5 production in the airways were diminished in Stat5a−/− mice and Stat5b−/− mice. Moreover, antigen-induced proliferation of splenocytes was diminished in Stat5a−/− mice and Stat5b−/− mice, suggesting that the generation of antigen-primed T cells may be compromised in Stat5a−/−mice and Stat5b−/− mice and this defect may account for the diminished antigen-induced T-cell infiltration into the airways. Interestingly, IL-4 and IL-5 production from anti-CD3–stimulated splenocytes was diminished in Stat5a−/− mice and Stat5b−/− mice. However, antigen-specific IgE and IgG1 production was diminished in Stat5a−/− mice but not in Stat5b−/− mice, whereas antigen-specific IgG2a production was increased in Stat5a−/− mice, suggesting the enhanced Th1 responses in Stat5a−/− mice. Finally, we found that eosinophilopoiesis induced by the administration of recombinant IL-5 was also diminished in Stat5a−/− mice and Stat5b−/− mice. Together, these results indicate that both Stat5a and Stat5b are essential for induction of antigen-induced eosinophil recruitment into the airways and that the defects in antigen-induced eosinophil recruitment in Stat5a−/− mice and Stat5b−/− mice result from both impaired IL-5 production in the airways and diminished IL-5 responsiveness of eosinophils.
Cutting Edge: Failure of Antigen-Specific CD4+ T Cell Recruitment to the Kidney during Systemic Candidiasis