Innate defenses in the liver during Listeria infection.

The majority of pathogens entering the bloodstream are cleared by the liver. Listeria monocytogenes, an important natural pathogen of humans, is a useful tool for examining protective immune responses during systemic infections of mice. Innate immunity contributes to blood clearance and eventual sterilization of the liver subsequent to Listeria infections. Effector mechanisms expressed in the liver early after infections are orchestrated by complex interactions between resident populations, i.e. hepatocytes and Kupffer cells, with infiltrating monocytes, neutrophils, and natural killer cells. These interactions include cell to cell contact through adhesion molecules, as well as communication through secretion of cytokines and chemokines. The liver environment, as the interface between blood-borne pathogens and innate host defenses, is reviewed here.