Studies on CD4~+CD25~+ T Regulatory Cells in Immune Tolerance Induced by Oral BCG

Objective: To investigate the influence of oral BCG on CD4+ CD25+ T regulatory cells in inducing immune tolerance.Methods: The EAE rats,induced by immunization with oral MBP,were randomly divided into BCG group(0.5mg/kg) and EAE group(PBS),with 15 rats per group,and 15 normal rats were used as control group.On 15d and 27d after treatment,CD4+ CD25+ T regulatory cells from peripheral blood,thymus and spleen were respectively determined by flow cytometry,and levels of serum IL-6,TGF-β,IgE and IgG were measured by ELISA.Results: Compared with EAE group,CD4+ CD25+ T regulatory cells from peripheral blood,thymus and spleen,and levels of IL-6 and TGF-β increased in BCG group after treatment,but serum IgE and IgG levels decreased.Conclusion: Oral BCG could induce immune tolerance by up-regulating the percentage of CD4+ CD25+ T regulatory cells,inhibiting effector T cell function.