TSLP is a hematopoietic cytokine that plays a critical role as regulator of T helper (T
H )2 driven inflammation. It is highly expressed in skin keratinocytes and airway epithelial cells as well as in gut and thymus. TSLP is an interleukin 7 (IL-7)-like cytokine that binds to a heterodimeric receptor complex consisting of the alpha chain of the IL-7 receptor (IL-7Rα) and the TSLP receptor chain (TSLPR). It is able to promote the activation of B cells and dendritic cells (DCs). TSLP activated DCs polarize naive CD4
+ T cells to differentiate into inflammatory T
H 2 cells that produce the pro-allergic cytokines IL-4, IL-5, IL-13, and TNF-α. Furthermore TSLP supports B cell expansion and differentiation. It induces the release of T cell-attracting chemokines from monocytes and enhances the maturation of CD11c
+ DCs. Like IL-7, TSLP has been shown to activate and phosphorylate the transcription factors STAT3 and STAT5.
