Complement Cascade Proteins

Complement cascade proteins are a group of plasma proteins that play a central role in the innate immune system. They circulate in the blood and tissues as inactive precursors, primarily synthesized by the liver. Upon activation by specific triggers—such as pathogens or antibody-antigen complexes—these proteins interact sequentially in a highly regulated enzymatic cascade, leading to various immune defense mechanisms. Key functions include opsonization, chemotaxis, cell lysis, and inflammation. The system comprises core components (C1–C9), regulatory proteins, and receptors. Activation occurs via the classical, lectin, and alternative pathways, converging on C3 cleavage. Regulation is critical to prevent host tissue damage, involving soluble and membrane-bound regulators. Defects can result in immunodeficiency or contribute to autoimmune diseases. Therapeutic interventions may target specific components or regulatory mechanisms.

Varies depending on the specific complement protein targeted; may involve inhibition of activation pathways or blockade of receptor interactions.