Staying local - antigen presentation in the liver

The liver is known as organ with unique immune competence. Besides its unique microenvironment that is determined by gut-derived portal venous blood constituents and the presence of enzymes with immune regulatory properties, liver antigen presenting cell populations regulate antigen-specific immunity in a local fashion. In addition to bone marrow-derived dendritic cells and myeloid cells such as macrophages and monocytes, also truly liver-resident cell populations function as antigen presenting cells such as liver sinusoidal endothelial cells and hepatocytes. The functional outcome of antigen-presentation by these cell populations is diverse and ranges from generation of regulatory CD4 cells, to induction of memory CD8 T cells or deletional tolerance, which generates a complex network of antigen-presenting cells that determines hepatic immune regulation and local immune surveillance against viral infection.