TSLP Directly Interacts with Skin-Homing Th2 Cells Highly Expressing its Receptor to Enhance IL-4 Production in Atopic Dermatitis.

Thymic stromal lymphopoietin (TSLP) is overtly expressed on skin lesions of atopic dermatitis (AD), and the initiative role of TSLP-activated DCs in AD has gained much attention in the past few years, while its actions on other immune cells such as T cells have been given less notice. We aimed to clarify whether TSLP receptor (TSLPR) is expressed on certain populations of T cells and whether TSLP possesses the capability to directly interact with T cells from AD patients. Peripheral lymphocytes from 51 AD patients are analyzed by flow cytometry, and ex vivo experiments using peripheral blood and lesional skin-derived T cells were conducted. TSLPR expression was defined to CD4+ T cells, and CD4+CCR4+CXCR3-CCR7-CCR10+CLA+ T cells in AD patients exhibited enhanced TSLPR expression. The frequency of TSLPR+CD4+ T cells correlated with disease activity. CD4+ T cells from AD patients directly interacted with TSLP to produce a higher amount of IL-4 than those from normal subjects, and this action was attenuated with anti-TSLPR antibody. The importance of IL-4 in the induction of TSLPR expression was found in AD T cells. Our findings indicate that T cells from AD patients possess strong potential to directly interact with TSLP to promote Th2 response.