Abstract: Objective To investigate the level of CD4+CD25+CD127low regulatory T cells in the peripheral blood of hepatocellular carcinoma (HCC) patients with HBV infection and to explore the relationship between these cells and HBV infection. Methods Peripheral blood mononuclear cells were isolated from 41 HCC patients infected with HBV, 34 HCC patients without HBV infection and 29 healthy persons. These mononuclear cells were labeled with the monoclonal antibodies of CD4, CD25 and CD127, and then they were determined by flow cytometry (FCM) to analyze the level of Tregs. Moreover, the load of HBV DNA in the blood serum of HCC patients with HBV infection was detected by fluorescent quantitative polymerase chain reaction (FQ-PCR). Results The percentage of CD4+CD25+CD127lowTregs in CD4+T cells in the HCC patients with HBV infection was higher than that in the HCC patients without HBV infection [(8.24±2.20)% vs (7.06±2.46)%, P<0.05] and that in the healthy persons [(8.24±2.20)% vs (6.51±1.99)%, P<0.01]. Furthermore, the percentage of CD4+CD25+CD127lowTregs in CD4+T cells in the HCC patients without HBV infection was higher than that in the healthy persons [(7.06±2.46)% vs (6.51±1.99)%, P<0.05]. In addition, the level of CD4+CD25+CD127lowTregs in the HCC patients with HBV infection was gradually increased following the increase of HBV DNA load and there was a positive correlation between the level of CD4+CD25+CD127lowTregs and the load of HBV DNA (r=0.350，P<0.05). Conclusion The level of CD4+CD25+CD127low Tregs in HCC patients is increased remarkably and associated with the copy of HBV DNA, which may be an important mechanism of immune evasion in HCC.

Key words: Hepatocellular Carcinoma (HCC), Hepatitis B Virus (HBV), Regulatory T Cells (Tregs), Immunologic Function, CD127