Cytokine that induces the release of T-cell-attracting chemokines from monocytes and, in particular, enhances the maturation of CD11c(+) dendritic cells. Can induce allergic inflammation by directly activating mast cells (By similarity). Interacts with a receptor composed of CRLF2 and IL7R. Binding of TSLP to CRLF2/TSLPR is a mechanistic prerequisite for recruitment of IL7R to the high-affinity ternary complex.