Activation of the plasma kinin forming cascade along cell surfaces

Proteins of the plasma kinin-forming cascade bind to endothelial cells and activation of the cascade can be initiated along the surface, The light cha in of high molecular weight kininogen (HK) (domain 5) and factor XII bind t o gC1qR, the heavy chain of HK (domain 3) binds to cytokeratin 1 and the in teractions are zinc dependent. Prekallikrein binds to domain 6 of HK. Antis era to gC1qR and cytokeratin 1 inhibit binding and activation. Incubation o f normal plasma with endothelial cells leads to gradual conversion of preka llikrein to kallikrein, while plasma deficient in factor XII or HK are inac tive within a 2-hour time frame. Thus factor XII is critical for activation to proceed. Augmentation of these reactions may occur when C1 inhibitor is functionally deficient or with ACE inhibitors which also inhibit kininases , Copyright (C) 2001 S.Karger AG, Basel.