Thymic stromal lymphopoietin (TSLP) is highly expressed by bronchial epithelial cells and skin keratinocytes in allergic diseases. TSLP acts as a master switch for allergic inflammation through the activation of dendritic cells and mast cells for initiating inflammatory type 2 T-helper lymphocyte (Th2) responses. To elucidate the immunological cascades of epithelium/keratinocyte-eosinophil mediated allergic inflammation, we examined the modulating effects of TSLP on human eosinophils. Expression of TSLP receptor complex was detected by RT-PCR, flow cytometry and Western blot. Adhesion molecules, cytokine and chemokines were quantitated by flow cytometry or ELISA. Intracellular signal transduction molecules were measured by Western blot and flow cytometry. We observed that human eosinophils constitutively expressed functional heterodimeric TSLP receptor complex comprising TSLP-binding chain TSLPR and interleukin (IL)-7R chain. TSLP could significantly delay eosinophil apoptosis, up-regulate cell surface expression of adhesion molecule CD18 and intercellular adhesion molecule-1 but down-regulate L-selectin, enhance eosinophil adhesion onto fibronectin, and induce the release of inflammatory cytokine IL-6 and chemokines CXCL8, CXCL1 and CCL2 (all p < 0.05). All these effects were concentration-dependent and TSLP-specific. TSLP regulated the above effects through the activation of extracellular signal-regulated protein kinase, p38 mitogen activated protein kinase and nuclear factor-B signaling pathway, but not signal transducer and activator of transcription (STAT)-5 and STAT-3 which were usually activated in other effector cells upon TSLP stimulation. Collectively, the above findings elucidated the pro-allergic mechanisms of TSLP via the activation of distinct intracellular signaling pathways in eosinophils.