Imoto S, et al. - This study was conducted to elucidate the factors affecting interferon-λ (IFNL) 3 production and to evaluate the roles of IFNL3 in acute hepatitis C (AHC). The physicians demonstrated that in AHC patients, serum IFNL3 levels at baseline were higher regardless of the rs8099917 polymorphism, and primary hepatitis C virus (HCV) infection triggered the production of IFNL3. Increased IFNL3 levels performed an important role as the first line of defense in the innate immune system against invading HCV, but serum IFNL3 levels were not the principal determinant of the clinical course of conventional AHC.