Interferon-α Abrogates Tolerance Induction by Human Tolerogenic Dendritic Cells

BACKGROUND: Administration of interferon-α (IFN-α) represents an approved adjuvant therapy as reported for malignancies like melanoma and several viral infections. In malignant diseases, tolerance processes are critically involved in tumor progression. In this study, the effect of IFN-α on tolerance induction by human tolerogenic dendritic cells (DC) was analyzed. We focussed on tolerogenic IL-10-modulated DC (IL-10 DC) that are known to induce anergic regulatory T cells (iTregs). METHODOLOGY/PRINCIPAL FINDINGS: IFN-α promoted an enhanced maturation of IL-10 DC as demonstrated by upregulation of the differentiation marker CD83 as well as costimulatory molecules. IFN-α treatment resulted in an increased capacity of DC to stimulate T cell activation compared to control tolerogenic DC. We observed a strengthened T cell proliferation and increased IFN-γ production of CD4(+) and CD8(+) T cells stimulated by IFN-α-DC, demonstrating a restoration of the immunogenic capacity of tolerogenic DC in the presence of IFN-α. Notably, restimulation experiments revealed that IFN-α treatment of tolerogenic DC abolished the induction of T cell anergy and suppressor function of iTregs. In contrast, IFN-α neither affected the priming of iTregs nor converted iTregs into effector T cells. CONCLUSIONS/SIGNIFICANCE: IFN-α inhibits the induction of T cell tolerance by reversing the tolerogenic function of human DC

Interferon-alpha suppresses liver cell proliferation in patients with chronic hepatitis C virus infection

Interferon (IFN) therapy has been shown to reduce the risk of hepatocellular carcinoma (HCC) in patients with chronic hepatitis C, including virological nonresponders (NR). Whether IFN suppresses liver cell proliferation, i.e. the relevant risk factor for HCC, is unknown. The aim of the study was to evaluate the effect of IFN therapy on liver cell proliferation in chronic hepatitis C. The proliferating cell nuclear antigen-labelling index (PCNA-LI) was assessed prior to and at the end of therapy in the liver of 29 patients with chronic hepatitis C who received 3 MU IFN-\u3b12b thrice weekly for 24-48 weeks. Overall, the median value of PCNA-LI was significantly reduced from 2.6% to 1.1% at the end of therapy (P 2 and >4 points reduction level (80% vs 36%, P = 0.02 and 53% vs 14%, P = 0.03, respectively). The study showed a significant suppression of liver cell proliferation in IFN-treated patients with chronic hepatitis C. Although the strongest IFN effect was observed in virological responders, a reduction of proliferative activity was also seen in virological NRs