A series of molecules that work together to perform many immune system functions. For example, the complement system helps to dissolve and remove immune complexes and to kill foreign cells.

A group of at least 20 blood proteins that cooperate with other defense mechanisms; may amplify the inflammatory response, enhance phagocytosis, or directly lyse pathogens; activated by the onset of t [..]

Proteins that kill viruses, bacteria, and other microbes directly or flag them for destruction by white blood cells.

a network of proteins and enzymes that interact with each other to protect the body against foreign substances, like bacteria and other invading organisms. aHUS is a disease in which the complement system has trouble figuring out who is “one of us” and who is “one of them”

The complement system is a group of proteins in the blood with immune functions. Through a complex cascade of biochemical interactions, complement can act to protect the body in several ways: complement can cause a foreign cell to burst open and die; it can mark a foreign cell for destruction by a macrophage; and it can result in inflammation and s [..]