Natural killer cells in viral hepatitis: facts and controversies
Article first published online: 29 JUN 2010
© 2010 The Authors. Journal Compilation © 2010 Stichting European Society for Clinical Investigation Journal Foundation
European Journal of Clinical Investigation
Volume 40, Issue 9, pages 851–863, September 2010
How to Cite
Mondelli, M. U., Varchetta, S. and Oliviero, B. (2010), Natural killer cells in viral hepatitis: facts and controversies. European Journal of Clinical Investigation, 40: 851–863. doi: 10.1111/j.1365-2362.2010.02332.x
- Issue published online: 5 AUG 2010
- Article first published online: 29 JUN 2010
- Received 30 April 2010; accepted 19 May 2010
- innate immunity;
- NK cells
Eur J Clin Invest 2010; 40 (9): 851–863
Background Hepatitis B virus (HBV) and hepatitis C virus (HCV) are major human hepatotropic pathogens responsible for a large number of chronic infections worldwide. Their persistence is thought to result from inefficiencies of innate and adaptive immune responses; however, very little information is available on the former. Natural killer (NK) cells are a major component of innate immunity and their activity is tightly regulated by several inhibitory and activating receptors.
Design In this review, we examine controversial findings regarding the role of NK cells in the pathogenesis of acute and chronic liver disease caused by HCV and HBV.
Results Recent studies built up on technical advances to identify NK receptors and their functional correlates in this setting. While NK cells seem to behave correctly during acute hepatitis, it would appear that the NK cytotoxic potential is generally conserved in chronic hepatitis, if not increased in the case of HCV. In contrast, their ability to secrete antiviral cytokines such as interferon ex vivo or after cytokine stimulation is severely impaired.
Conclusions Current evidence suggests the existence of an NK cell functional dichotomy, which may contribute to virus persistence, while maintaining low-level chronic liver inflammation. The study of liver-infiltrating NK cells is still at the very beginning, but it is likely that it will shed more light on the role of this simple and at the same time complex innate immune cell in liver disease.