The regulation of the complement system: insights from genetically-engineered mice.

The complement system is very tightly regulated by fluid-phase and membrane-bound factors that prevent injury to self-tissues. The study of genetically engineered animals with targeted deletion or gain of function mutations has highlighted the important role that many of the complement inhibitors play in vivo. The advantages and disadvantages of this type of approach are discussed and the insights gained from the investigation of these animals are reviewed.