Ribavirin Does Not Impair the Suppressive Activity of Foxp3＋CD4＋CD25＋ Regulatory T Cells

Abstract

Ribavirin is an antiviral drug used in combination with pegylated interferon-α (IFN-α) for the treatment of hepatitis C virus (HCV) infection. Recently, ribavirin was reported to inhibit the suppressive activity of regulatory T (Treg) cells. In the present study, we re-evaluated the effect of ribavirin on Foxp3＋CD4＋CD25＋ Treg cells from normal donors. First,we examined the expression of CTLA-4 and CD39, which are known to play a role in the suppressive function of Treg cells. We found that ribavirin treatment did not modulate the expression of CTLA-4 and CD39 in Treg cells. We also studied the effect of ribavirin on Treg cells in the presence of IFN-α;however, the expression of CTLA-4 and CD39 in Treg cells was not changed by ribavirin in the presence of IFN-α. Next,we directly evaluated the effect of ribavirin on the suppressive activity of Treg cells in the standard Treg suppression assay, by co-culturing CFSE-labeled non-Treg CD4＋ T cells with purified Treg cells. We found that ribavirin did not attenuate the suppressive activity of Treg cells. Taken together,while ribavirin reversed Treg cell-mediated suppression of effector T cells in the previous study, we herein demonstrate that ribavirin does not impair the suppressive activity of Treg cells.