IFN- alpha blocks IL-17 production by peripheral blood mononuclear cells in patients with chronic active hepatitis B Infection

BACKGROUND: IFN-α has been used to treat patients with chronic active hepatitis B (CAHB). Recent studies have implicated the IL-23/Th-17 pathway in the pathogenesis of CAHB. In this study, we investigated whether IFN-α could affect this pathway. METHODS: Peripheral blood mononuclear cells (PBMCs) obtained from patients with active CAHB (n = 61) and controls (n = 32) were cultured with or without IFN-α, and the levels of IL-17 and IL-10 in the supernatants were determined by ELISA, while the frequency of IL-17-expressing cells was measured by FACS. Similar experiments were also conducted with isolated CD4+ T cells from controls. Furthermore, an experiment using an anti-IL-10 antibody was performed to examine the underlying mechanisms of action of IFN-α. RESULTS: Both the levels of IL-17 and the frequency of IL-17-expressing cells were significantly higher in the PBMCs from CAHB patients than in the controls. IFN-α significantly decreased IL-17 production and the frequency of IL-17-expressing cells in PBMCs from both patients and controls. On the other hand, IFN-α increased IL-10 production by PBMCs from patients and controls. Anti-IL-10 antibody was able to neutralize the inhibitory effect of IFN-α on IL-17 production by PBMCs. CONCLUSIONS: In vitro experiments showed that IFN-α could inhibit IL-17 expression and increase IL-10 production by PBMCs and CD4+ T cells. The inhibitory role of IFN-α on IL-17 production was partly mediated by IL-10.