Thymic Stromal Lymphopoietin promoted CD4<sup>+</sup>CD25<sup>-</sup> T cells differentiation isolated from the thymus of patients with Myasthenia Gravis to CD4<sup>+</sup>CD25<sup>+</sup> Regulatory T Cells In Vitro

Thymic stromal lymphopoietin (TSLP) is a cytokine and is closely related to Interleukin (IL) - 7, and hTSLP can activation through the human thymus dendritic cell in thymic to indirectly promote the differentiation of natural Regulatory T cells (Tregs) of the thymus. In this study, we focused on recombinant TSLP to determine its effects on the differentiation of CD4+CD25-T cells separated from the thymus of myasthenia gravis (MG) patients. Our results demonstrated that exogenous TSLP could increase CD4+CD25+T/CD4+T cells ratio, up-regulate the expression of Foxp3 mRNA and protein expression in CD4+CD25+Treg cells. Furthermore, we found that CD4+CD25+ Treg cells induced by exogenous TSLP could secrete IL - 10, Transforming growth factor (TGF) - β and the ability to inhibit CD4+T cell proliferation improved. These results indicate that TSLP may promote the differentiation of thymic CD4+CD25-T cells of MG patient to CD4+CD25+Foxp3+ regulatory T cells and enhance the function of immune suppression.