The study investigates the role of epithelial cells in triggering allergic inflammation through the production of thymic stromal lymphopoietin (TSLP). TSLP is shown to activate CD11c+ dendritic cells (DCs) and induce the production of Th2-attracting chemokines TARC and MDC. TSLP-activated DCs prime naive T helper 2 (TH2) cells to produce proallergic cytokines such as IL-4, IL-5, IL-13, and tumor necrosis factor-α, while down-regulating IL-10 and interferon-γ. TSLP is highly expressed by epithelial cells, particularly keratinocytes from patients with atopic dermatitis, and is associated with Langerhans cell migration and activation. These findings suggest that TSLP plays a crucial role in initiating allergic inflammation by acting as a key cytokine produced by epithelial cells or keratinocytes.The study investigates the role of epithelial cells in triggering allergic inflammation through the production of thymic stromal lymphopoietin (TSLP). TSLP is shown to activate CD11c+ dendritic cells (DCs) and induce the production of Th2-attracting chemokines TARC and MDC. TSLP-activated DCs prime naive T helper 2 (TH2) cells to produce proallergic cytokines such as IL-4, IL-5, IL-13, and tumor necrosis factor-α, while down-regulating IL-10 and interferon-γ. TSLP is highly expressed by epithelial cells, particularly keratinocytes from patients with atopic dermatitis, and is associated with Langerhans cell migration and activation. These findings suggest that TSLP plays a crucial role in initiating allergic inflammation by acting as a key cytokine produced by epithelial cells or keratinocytes.