Background：Interleukin-31(IL-31) is a newly discovered four-helix bundle cytokine and expressed by several types of cells under both normal and disease state, such as activated CD4+T cells, mast cells, monocytes, macrophages, immature and mature monocyte-derived dendritic cells and so on. IL-31 signals through a heterodimeric receptor complex consisting of the IL31 receptor alpha(IL31Rα) and the oncostatin
