Lymphocyte recruitment to the liver: Molecular insights into the pathogenesis of liver injury and hepatitis

Recirculation of blood lymphocytes through the liver occurs under normal conditions as part of the process of immune surveillance. In response to injury or infection recruitment from blood increases and the nature and distribution of the infiltrate will determine the type and outcome of the resulting hepatitis. Recruitment from blood occurs via the hepatic sinusoids and is controlled by interactions between circulating lymphocytes and the highly specialised sinusoidal endothelial cells. This is a low flow vascular bed and the molecular basis of recruitment differs from other tissues. In this review we outline the molecular basis of lymphocyte recruitment to the liver and the effect on it of the local tissue microenvironment and how dysregulation of these processes can lead to uncontrolled inflammation and liver damage.