It has been reported that transgenic expression of IL-9 in the lungs of mice resulted in extensive airway inflammation (28, 39), and IL-9 deficiency in Experimental autoimmune encephalomyelitis (EAE) mice reduces T cell infiltration and decreases IL-17 and IFN-γ production in CNS (40), which indicates that IL-9 plays critical roles in tissue inflammation. This evidence concerns the gene IL17A and experimental autoimmune encephalomyelitis.