CD161(+)CD4(+) T cells are enriched in the liver during chronic hepatitis and associated with co-secretion of IL-22 and IFN-γ.

Journal article

Hepatitis C virus infection is a major cause of chronic liver disease. CD4(+) T cells play a key role in disease outcome. However, the critical functions and associated phenotypes of intrahepatic CD4(+) T cells are not well defined. We have previously shown that CD8(+) T cells expressing the C type lectin CD161 are highly enriched in the human liver, especially during chronic hepatitis. These cells are associated with a type 17 differentiation pattern and express cytokines including IL-17A, IL-22, and IFN-γ. We therefore analyzed expression of CD161 on CD4(+) T cells in blood and liver and addressed the relevant phenotype and functional capacity of these populations. We observed marked enrichment of CD161(+)CD4(+) T cells in the liver during chronic hepatitis such that they are the dominant subtype (mean 55% of CD4(+) T cells). IL-22 and IL-17 secreting CD4(+) T cells were readily found in the livers of HCV(+) and NASH donors, although not enriched compared to blood. There was, however, specific enrichment of a novel subset of IL-22/IFN-γ dual secretors (p = 0.02) compared to blood, a result reconfirmed with direct ex vivo analyses. These data indicate the dominance of CD161(+) expressing lymphocyte populations within the hepatic infiltrate, associated with a distinct cytokine profile. Given their documented roles as antiviral and hepatoprotective cytokines respectively, the impact of co-secretion of IFN-γ and IL-22 in the liver may be particularly significant.

Authors: Kang, Y; Seigel, B; Bengsch, B; Fleming, V; Billerbeck, E

• Journal: Frontiers in immunology
• Volume: 3
• Issue: NOV
• Pages: 346
• Publication date: 2012-01-01
• DOI: 10.3389/fimmu.2012.00346
• EISSN: 1664-3224
• Language: English
• Keywords: CD4+ T cell; IL-22; hepatic inflammation; CD161; HCV