Hepatitis C Virus (HCV) infection affects more than 200 million individuals worldwide. Only a fraction of infected individuals clear the virus, whereas the majority (70%) develops chronic infection. The current standard of care, pegylated interferon/ ribavirin (pegIFN/rib) is effective in only 50% of patients. Patients who fail anti-viral therapy gradually progress to end-stage liver disease and hepatocellular cancer; which can only be cured by a liver transplant. The reasons for treatment failure are unclear but involve both viral and host factors. One significant factor may be impaired T cell function. Chronic HCV infection is associated with functionally impaired or exhausted cytotoxic T lymphocytes (CTLs), with decreased anti-viral cytokine production, cytotoxicity and proliferative capacity. The investigators recently showed that many patients who fail treatment have elevated frequencies of CD4+CD25+Foxp3+regulatory T cells (Tregs) producing the novel fibrinogen-like-protein 2 (FGL2/fibroleukin) which appears to impair HCV specific immune responses. Binding of FGL2 to the FcγRIIB receptor leads to inhibition of dendritic cell (DC) maturation, B cell apoptosis and inhibition of development of effective CD4+and CD8+T and B cell anti-viral responses. In HCV, increased levels of secreted FGL2 may suppress anti-viral immune responses and promote disease progression.