The Liver as a Pivotal Innate Immune Organ

Summaryliver contains innate immune leukocytes, macrophages (Kupffer cells), natural killer cells and natural killer T cells, all of which participate in the defense against bacteria and tumors by producing proinflammatory cytokines. However, these cells are also sometimes involved in hepatocyte injury, septic shock and multi-organ failure. Kupffer cells are subclassified into two major subsets: one that is responsible for phagocytosis and reactive oxygen species production and another that is responsible for cytokine production. Mouse B-2 cells are also subclassified into two major subsets: one that produces IgM (but not cytokines) and another that produces interleukin-12 (but few IgM) in response to lipopolysaccharides. The latter type is predominantly present in the liver and shows phagocytic and bactericidal activities. Therefore, all hepatic mononuclear cells play important roles in the T-helper 1 response and innate immunity, thereby acting against infections and tumors. Immunogastroenterology 2012; 1:76-89