Kupffer cells and their function.

The intention of this review is to stress new information regarding the quite versatile functions of Kupffer cells. Although their main function is phagocytosis and defence of the liver against bacteria, endotoxaemia and viral infections, they also fulfil other important roles. They will phagocytose and partially degrade bacterial antigens before handing them on to the hepatocytes for excretion into the bile. They handle LDL lipoproteins, whilst the HDL proceed directly into the hepatocytes. They produce lymphokine mediators that direct protein synthesis by the hepatocytes. Also they normally produce prostaglandins that are cyto-protective for the hepatocytes. Conversely, if they are required to attack infected hepatocytes or cancer cells, then they switch to the production of leukotrienes. Thus they function as specialised macrophages, and it is not surprising that other "activated macrophages" have to be recruited into the liver to support them in inflammatory reactions.