In allergic diseases, the hyperresponsiveness is developed in various organs, though the mechanism of its onset has not been elucidated. Based on our previous research, this study aimed to identify hyperresponsiveness-inducing factors by verifying the hypothesis "Molecules that are commonly produced / expressed by various T cell subsets cause hypersensitivity". Through the search for hyperresponsiveness-inducing factors, functional verification of candidate molecules, and re-evaluation of T cell-dependent hyperresponsiveness mouse models, we elucidated the possibility, with its underlying mechanisms, that neuropeptides produced by T cells are involved in the development of hyperresponsiveness. Furthermore, the requirement of reanalysis of the hyperresponsiveness-inducing factors, with considering the differences among the target organs as well as the biological responses, was suggested.