Endocytosis Kupffer cells

The liver eliminates proteins on first pass after oral administration and on each pass of hepatic blood flow. Hepatocytes, Kupffer cells, adipocytes, and endothelial cells can all be involved in proteolysis (Figure 5.6). Proteolysis can occur in lysosomes after endocytosis of a protein and lysosomal fusion. Endocytosis of a protein may be a nonspecific or receptor-mediated process. Proteolytic products are eliminated from the liver through biliary excretion, and subsequently digested further in the intestinal tract. 

Toth, C.A., Thomas, R Liver endocytosis and Kupffer cells. Hepatology 1992 16 255-266... 

This cooperation not only takes place between the sinusoidal cells, but also with the hepatocytes .) endothelial and Kupffer cells complement each other through various mechanisms of endocytosis and different pathways of enzymatic clearance (2.) as a double barrier, they protect the liver cells both from toxic and undesired substances, even to the extent of self-sacrifice (i.) they intervene in the metabolism of liver cells with self-produced substances 4.) they send signal substances like cytokines (e.g. interferons) and eicosanoids (e.g. leukotrienes) to the liver cells for independent control of biochemical and biomolecular reaction cascades. 

The reticuloendothelial system (RES) as a part of the host defense mechanism for the clearance of foreign macromolecules and particles includes several types of macrophages, which are mobile cells with particularly prominent endocytosis, able to transport endocytosed substances from the inner compartments by active motion. Kupffer cells of liver (Fig. 7, 9), reticulocytes of spleen and bone marrow, etc. are other components of RES which are in direct contact with blood. The cells of RES are responsible for a major part of the polymer accumulation from the central compartment... 

B. Smedsrod, J. Melkko, N. Araki, H. Sano, and S. Horiuchi. Advanced glycation end products are eliminated by scavenger-receptor-mediated endocytosis in hepatic sinusoidal Kupffer and endothelial cells, Biochem. J. 322 567-573 (1997). 

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