Characterization of Th9 Cells in the Development of EAE and IBD.

Encephalitogenic and colitogenic effector T cells have been implicated in the induction of experimental autoimmune encephalomyelitis (EAE) and inflammatory bowel disease (IBD), respectively. Effector functions of Th1 and Th17 cells have been well characterized and described for the induction and development of EAE and IBD; however, the recently identified Th9 cells have also been suggested to play an important role in these autoimmune pathologies. Th9 cells, primarily characterized by their high level of production of IL-9, are not only essential in controlling extracellular pathogens but also contribute to the development of autoimmunity and allergic inflammation. Furthermore, it was also demonstrated that IL-9 promotes Th17 cell-mediated tissue pathology in EAE and it compromises the barrier functions of the gut in IBD. In vivo adoptive transfer of in vitro differentiated Th9 cells induces the development of autoimmune tissue inflammation in EAE and IBD. Here we describe methods for in vitro differentiation of naïve murine CD4+ T cells to generate IL-9-producing Th9 cells and follow their effector functions in EAE and IBD murine models.