Importance of Th17‐ and Th1‐Associated Responses for the Development of Asthma

Bronchial asthma was believed to be mediated by Th2 cells and their cytokines. However, other subsets of CD4+ T cells, such as T helper 17 (Th17) cells, regulatory T cells, and Th1-derived cells with unique functional properties, are now recognized as having a role in the modulation of atopic diseases exemplified by asthma and atopic dermatitis. In this chapter, we focus on Th17 cells and recently identified subpopulation of Th1 cells that express both Th1 and Th2 cytokines in response to the engagement via their T-cell receptor and interleukin 18 receptor (IL-18R) and review their roles in the pathogenesis of bronchial asthma.