Dendritic cells, the liver, and transplantation

Interstitial liver dendritic cells (DCs) exhibit phenotypic diversity and functional plasticity. They play important roles in both innate and adaptive immunity. Their comparatively low inherent T cell stimulatory ability and the outcome of their interactions with CD4(+) and CD8(+) T cells, as well as with natural killer (NK) T cells and NK cells within the liver, may contribute to regulation of hepatic inflammatory responses and liver allograft outcome. Liver DCs migrate in the steady state and after liver transplantation to secondary lymphoid tissues, where the outcome of their interaction with antigen-specific T cells determines the balance between tolerance and immunity. Systemic and local environmental factors that are modulated by ischemia-reperfusion injury, liver regeneration, microbial infection, and malignancy influence hepatic DC migration, maturation, and function. Current research in DC biology is providing new insights into the role of these important antigen-presenting cells in the complex events that affect liver transplant outcome.