Re: what cell is responsible for realeasing complement

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