Adhesion of lymphocytes to hepatic endothelium.

Chronic inflammation occurs when factors that regulate the process of leucocyte recruitment are disrupted, and it is dependent on recruitment, activation, and retention of lymphocytes within tissue microenvironments. The molecular mechanisms that mediate lymphocyte adhesion to vascular endothelial cells have been described by several groups, but the signals involved in the recruitment of lymphocytes via the hepatic circulation have yet to be elucidated fully. This article considers the liver as a model of organ specific lymphocyte recruitment. In this context, the roles of leucocyte and endothelial adhesion molecules and chemokines in lymphocyte recruitment are discussed. The article also reviews the mechanisms that regulate lymphocyte recirculation to the liver under both physiological and pathological conditions and draws parallels with other organs such as the gut and skin.