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.