To investigate whether increased soluble CD81 levels are associated with disease activity in chronic HCV infection, we compared soluble CD81 serum levels in patients with chronic hepatitis C to a cohort of patients with HCV infection but persistently normal ALT levels as ALT is a surrogate marker for apoptosis and necroinflammation in chronic hepatitis C. It is estimated that approximately 30% of patients with HCV show normal ALT levels [35]. Here, CD81 is linked to chronic hepatitis C virus infection.