Role of Immune Cells in Hepatitis B Infection

Hepatitis B virus infection is a common cause of liver cirrhosis and hepatocellular carcinoma leading to about one million deaths annually. The disease pathogenesis is complex and incompletely understood, especially when it turns chronic. Among various factors known to be responsible for the disease progression, the immune system has the most important role to play. Viral clearance is largely T cells dependent, and progression to a chronic state is due to insufficient T cells response, partly due to T-regulatory cells. In chronic infections, functions of important immune cells like natural killer cells and dendritic cells are impaired, which enables the viral persistence and promotes the pathogenesis in the host body. Similarly, the virus is reported to modulate functions of monocytes, macrophages, and Kupffer cells to promote an immune-tolerant local environment in the liver. Though B cells are expected to be central to the humoral immune response that clears the virus, its role in chronic HBV is still obscure. This chapter would elaborate on the significant roles of immune cells in pathogenesis and in clearance of the hepatitis B virus.