Inhibition of NFAT specifically in T cells prevents allergic pulmonary inflammation.

NFAT is a family of transcription factors important in the regulation of cytokine genes and is widely expressed in different lymphoid and nonlymphoid tissues. Consequently, the role of NFAT in CD4+ T cells during an in vivo immune response is not completely clear. In this study, we use transgenic mice expressing a dominant negative NFAT mutant exclusively in T cells to address the role of NFAT in T cells during a Th2 immune response in a model of allergic airway inflammation. We have observed that inhibition of NFAT in T cells results in a reduction of Ag-specific Th2 Ab levels and IL-4 production by CD4+ T cells. The accumulation of eosinophils in the bronchoalveolar lavage is delayed in dominant negative NFAT-transgenic mice. These mice are also more resistant to the development of lung pathology in response to allergen exposure. We, therefore, conclude that activation of NFAT in CD4+ T cells is required for the development of a Th2 immune response in vivo and allergic airway inflammation.