Characteristics of regulatory T-cell function in patients with chronic hepatitis B and C coinfection

Regulatory T cells (Tregs) affect the pathogenesis and disease progression of chronic viral hepatitis. This study evaluated the frequency and function of Tregs in patients with chronic HBV/HCV coinfection. Seventy-four untreated HBV/HCV co-infected patients were enrolled in this study. These subjects were divided into four subgroups: HBV-active/HCV-active (BACA), HBV-inactive/HCV-active (BICA), HBV-active/HCV-inactive (BACI) and HBV-inactive/HCV-inactive (BICI). Treg frequency was calculated as the fraction of CD4⁺ Foxp3⁺ T cells among CD4⁺ T cells. Treg-mediated inhibition was measured as percent of inhibition of T-cell proliferation. The expression of interferon (IFN)-γ, tumour necrosis factor (TNF)-α and interleukin (IL)-10 with/without Treg inhibition was also studied. Among the patients, there were 8 cases of BACA (10.8%), 38 of BICA (51.4%), 14 of BACI (18.9%) and 14 of BICI (18.9%). The frequency of CD4⁺ Foxp3⁺ T cells was comparable between the four groups. The inhibitory function of Tregs among the patients in the BACA and BICA was higher than that in the BICI (BACA vs BICI, P = .0210; BICA vs BICI, P = .0301). Patients in the BACA and BICA had higher fibrosis-4 (FIB-4) scores and serum ALT levels and lower serum albumin levels than those of the other groups. ALT abnormality was significantly and independently associated with a higher Treg immunosuppressive ability. The IFN-γ expression of the effector T cells in the BACA was higher than that of the other groups. In conclusion, the inhibitory function of Tregs is higher among the HBV/HCV co-infected patients with active HCV infection. ALT abnormality plays a dominant role in Treg function.