Differential antigen specificity of hepatitis C virus-specific interleukin 17- and interferon γ-producing CD8(+) T cells during chronic infection.

A subset of CD8(+) T cells can secrete interleukin 17 (IL-17). However, very little information is currently available about their antigen specificity, tissue distribution, and biological relevance in chronic human viral infection. To address these issues, we comprehensively analyzed peripheral and intrahepatic CD8(+) T-cell responses in a cohort of patients with chronic hepatitis C virus (HCV) infection for the antigen-specific production of IL-17 and interferon (IFN) γ. We found that HCV-specific IL-17-producing and retinoic acid receptor related orphan receptorγt-expressing CD8(+) T cells are detectable in blood and liver and target different epitopes, compared with IFN-γ-producing CD8(+) T cells. Their highest frequency was found in patients with low inflammatory activity, suggesting a protective role in chronic HCV infection.