Objective:To investigate the roles of PD-1 and PD-L1,as well as related cytokines TGF-βand IL-10 in patients infected with Brucella.Methods:The expression of PD-1/PD-L1 in peripheral blood mononuclear cell CD 3+T cells,CD4+T cells,CD8+T cells,and dendrites cells was detected by flow cytometry in 60 patients infected with Brucella and 34 patients receiving follow-up cured and 60 healthy controls,the serum levels of TGF-βand IL-10 were detected by CBA.The correlations of PD-1 with TGF-βand IL-10 levels in patients infected with Brucella were analyzed by pearson correlation test .Results: Compared with control,brucellosis patients had the higher PD-1/PD-L1,TGF-βand IL-10 expression (P<0.05),while in the patients receiving follow-up cured,the PD-1/PD-L1,TGF-βand IL-10 were remarkably lower than those in pretherapy (P<0.01),the change of PD-1 was positively correlated with the levels of TGF-β(r=0.817,P<0.01) and IL-10 (r=0.835,P<0.01).Conclusion: High expression of PD-1/PD-L1 and TGF-βand IL-10 in patients with Brucella may be involved in the negative regulation of Brucella on host immune response .