I nterleukin （I L）-21, a cytokine produced by activated CD4＋ T cells, has broad pleiotropic actions that affect the functions of a variety of lymphoid cells. The roles of IL-21 in modulating immunity to infections ...I nterleukin （I L）-21, a cytokine produced by activated CD4＋ T cells, has broad pleiotropic actions that affect the functions of a variety of lymphoid cells. The roles of IL-21 in modulating immunity to infections are currently being defined. Notably, IL-21-mediated cellular and humoral immune responses play an important role in determining the outcome of viral infection. This article reviews the current knowledge on the critical role of IL-21 in hepatitis B virus （HBV） infection. As a competent intermediary, IL-21 derived from virus-specific CD4＋ T cells plays key roles in sustaining CD8＋ T cells and promoting B-cell responses that are essential for effective viral control. However, as a mediator of inflammation, I L-21 is also involved in the development of HBV-induced liver cirrhosis and exacerbating liver injury. Overall, the current data point to IL-21 as an immunomodulatory cytokine in HBV infection. Immunotherapeutic strategies aimed at optimizing the beneficial effects of IL-21 in HBV infection may prove to be a rigorous challenge in the future, as they should foster the strengths of IL-21 while circumventing potential drawbacks.展开更多
基金The authors express their sincere thanks to Drs Xiaoyong Zhang and Chris Kafai Li for their critical comments. This work was supported by the Major Science and Technology Special Project of China （2008ZX10002-004, 2012ZX10002-003 and 2011CB946100） and the National Natural Science Foundation of China （81270025）.
文摘I nterleukin （I L）-21, a cytokine produced by activated CD4＋ T cells, has broad pleiotropic actions that affect the functions of a variety of lymphoid cells. The roles of IL-21 in modulating immunity to infections are currently being defined. Notably, IL-21-mediated cellular and humoral immune responses play an important role in determining the outcome of viral infection. This article reviews the current knowledge on the critical role of IL-21 in hepatitis B virus （HBV） infection. As a competent intermediary, IL-21 derived from virus-specific CD4＋ T cells plays key roles in sustaining CD8＋ T cells and promoting B-cell responses that are essential for effective viral control. However, as a mediator of inflammation, I L-21 is also involved in the development of HBV-induced liver cirrhosis and exacerbating liver injury. Overall, the current data point to IL-21 as an immunomodulatory cytokine in HBV infection. Immunotherapeutic strategies aimed at optimizing the beneficial effects of IL-21 in HBV infection may prove to be a rigorous challenge in the future, as they should foster the strengths of IL-21 while circumventing potential drawbacks.
