TSLP is a hemopoietic protein that is expressed in the heart, liver and prostate. TSLP overlaps biological activities with IL-7, and binds with the heterodimeric receptor complex consisting of the IL-7R alpha-chain (IL-7Ralpha) and the TSLP-specific chain (TSLPR). Like IL-7, TSLP induces phosphorylation of STAT3 and STAT5, but uses kinases other than the JAKs for activation. TSLP prohibits apoptosis and stimulates growth of the human acute myeloid leukemia (AML)-derived cell line MUTZ3. It induces the release of T cell-attracting chemokines TARC and MDC from monocytes, and activates CD11c(+) dendritic cells (DCs). TSLP-activated DCs have been shown to prime naive T cells to produce the proallergic cytokines (IL-4, IL-5, IL-13, TNF-alpha) while down-regulating IL-10 and IFN-gamma, suggesting a role in initiating allergic inflammation. Recombinant Human TSLP is a 15.0 kDa protein consisting of 132 amino acid residues.