What is the role of the complement system in immunity?

The complement system plays a critical role in the immune response primarily by enhancing the ability of antibodies and phagocytes to clear pathogens. It consists of a series of proteins that work in tandem to opsonize pathogens, making them more recognizable and easier to engulf by phagocytic cells like macrophages and neutrophils.

When the complement system is activated, it can lead to a cascade of reactions that results in the formation of membrane attack complexes. These complexes can directly lyse some pathogens, but the more important function is the opsonization process. Opsonization labels pathogens with complement proteins, which facilitate their recognition by immune cells. Antibodies can also engage with complement proteins to form immune complexes further enhancing their clearance.

This cooperative relationship between the complement system, antibodies, and phagocytes is crucial for a robust immune response. By amplifying the effectiveness of these components, the complement system ensures that infections can be more efficiently managed and cleared from the body.