|MadSci Network: Immunology|
The liver (hepatocytes more specifically) produces about 90% of the complement found in blood. However, many cell types can produce complement proteins as essentially all cells express complement regulatory proteins to protect themselves from complement-mediated damage. So the remaining 10% of blood complement comes from a variety of cell types (probably leukocytes, endothelial cells and fibroblasts). Most cell types do not make complement proteins unless stimulated by infection, trauma or autoimmune disease. Under those circumstances, most cells can produce many of the complement proteins and this local production may be very important for controlling infection. The other side of the coin is that local production can contribute to damage of host tissue as well. Ref. Immunology, Kuby 5th edition 2003
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