Study of liver‐targeted regulatory T cells in hepatitis B and C virus in chronically infected patients

Introduction: Regulatory T cells (Tregs) play a critical role in chronic viral infections. The role of Tregs in chronic hepatitis B (CHB) and chronic hepatitis C (CHC) is unknown. This study examined the distribution and frequency of forkhead box p3⁺ (Foxp3⁺) Tregs in the liver tissue and compared the clinicopathological characteristics of CHB and CHC patients. Methods: Liver needle biopsies were obtained from 26 patients who were hepatitis B surface antigen positive and 27 patients who were hepatitis C virus antibody positive. Results: The ratio of Foxp3⁺ Tregs in CD3⁺ T cells was similar in HBV and in HCV cases. In HBV cases, the variables that were positively associated with the ratio of Foxp3⁺ Tregs in CD3⁺ T cells included the serum alanine aminotransferase level (R=0.402, P=0.025) and the ratio of CD8⁺ T cell plus CD56⁺ NK cell against CD4⁺ T cell (R=0.53, P=0.005). The ratio of Foxp3⁺ Tregs in CD3⁺ T cells increased more in the severe activity group than in the mild activity group (P=0.04). In HCV cases, the ratio of Foxp3⁺ Tregs in CD3⁺ T cells increased significantly in terms of the genotype2 (P=0.0002) and male gender (P=0.04). In addition, the ratio of Foxp3⁺ Tregs in CD3⁺ T cells showed a negative correlation with the ratio of CD8⁺ T cell plus CD56⁺ NK cell against CD4⁺ T cell (R=?0.508, P=0.005) and HCV viral load (R=?0.482, P=0.001). Conclusions: Liver‐targeted regulatory T cells present similarly in CHB and CHC, but their relationship with the effector cell population, the inflammation grade or the viral load is different between CHB and CHC.