We herein demonstrated that a substantial reduction in thymic export was observed in HCV-infected patients, during the first months of IFNa therapy. This effect directly paralleled IFNainduced lymphocytopenia and decreased IL-7 plasma levels, initially high in HCV-infected patients. These data suggest that IL-7 production by the liver, a consequence of active HCV replication, was reduced while patients controlled HCV viremia. Restricted IL-7 plasma levels might, in association with the antiproliferative effect of IFNa, limit T-cell production in the thymus. Our study highlights the therapeutic potential of IL-7 as a complement to the standard IFNa based treatment to help HCVinfected patients to sustain normal circulating T-cell counts, and restore the diversity of the peripheral T-cell repertoire through its central thymopoietic effect. Restoring the breadth and intensity of T-cell control over the HCV virus might be immediately beneficial for the HIV/HCV co-infected population and offer new promising avenues for chronic HCV in the context of massive drop of HCV viral load after short term treatment with new antiviral compounds that will continue to be administered in combination with IFNa [50] .