Plasma contact system (CS) (CS)

The plasma contact system (CS) is a complex biochemical cascade involving the interaction of Factor XII (FXII), prekallikrein (PK), and high-molecular-weight kininogen (HMWK) on negatively charged surfaces (Schmaier, 2016, PMID: 26824637). Upon activation, FXII is converted to FXIIa, which subsequently converts PK to plasma kallikrein, creating a positive feedback loop and leading to the release of the potent vasodilator bradykinin from HMWK (StatPearls, 2023). While the system contributes to the intrinsic pathway of blood coagulation, it is primarily recognized for its role in mediating inflammatory responses and vascular permeability (Long et al., 2016, PMID: 26538515). Pathological overactivation of this system is a hallmark of hereditary angioedema (HAE) and is implicated in the development of thromboembolic diseases and sepsis (Wu, 2015, PMID: 25617148). Modern therapeutic strategies focus on inhibiting specific components like FXIIa or plasma kallikrein to treat HAE and provide anticoagulation that does not compromise normal hemostasis (FDA, 2018). Consequently, the contact system represents a high-value target for precision medicine in both rare genetic disorders and common cardiovascular conditions.

Other names

Contact activation systemIntrinsic pathway of coagulationKinin-kallikrein systemFXII-dependent pathway

Inhibition of plasma kallikrein activity or Factor XII activation to prevent the generation of bradykinin and the initiation of the intrinsic coagulation cascade.