[Effect of mesenchymal stem cells on human Th1 cells by flow cytometry]

This study was aimed to investigate the effect of fetal bone marrow-derived mesenchymal stem cells (FBM-MSC) on the development of human Th1 cells. FBM-MSC were isolated, cultured and expanded in vitro. The cells were identified by their phenotype profiles and differential capacity. Human CD4(+) T cells from healthy donors were cultured alone or co-cultured with FBM-MSC (FBM-MSC/CD4). In these two cultures, the quantities of Th1 cells (interferon-γ(+)) were analyzed by flow cytometry. The results indicated that the immunophenotype and multilineage differentiation of FBM-MSC satisfied the generally accepted criteria. FBM-MSC played an inhibitory role in the development of Th1 cells. Flow cytometry analysis showed that the percentage of Th1 cells in FBM-MSC/CD4 was significantly lower than that in CD4(+) T cells cultured alone. The protein level of IFN-γ in FBM-MSC/CD4 detected by ELISA was also lower than that in CD4(+) T cells cultured alone. It was also demonstrated that the expression level of IL-6 in FBM-MSC/CD4 was much higher than that in CD4(+) T cells cultured alone or FBM-MSC. The neutralizing antibody of IL-6 could increase the quantities of Th1 cells and the expression levels of IFN-γ. It is concluded that FBM-MSC may play an inhibitory role in the development of human Th1 cells, and the IL-6 pathway may be one of mechanisms involved in the inhibitory role.