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Introduction

Plasma cascade systems with emphasis on the role of C1-inhibitor
The plasma cascade systems consist of proteins in the complement, kallikrein-kinin, coagulation and fibrinolytic systems which each have specialised functions. Cascade mechanisms include
(+=amplify, - = inhibition)

· Autoactivation or activation by an external initiator
· Sequential activation by limited proteolytic cleavage or build-up of macromolecular complexes (+).
· One activated molecule activates several molecules at the next step yielding an exponential amplification (+).
· Amplification of the response by positive feedback (+).
· Use of binding/helper proteins to bring reactants together (+).
· Spontaneous or accelerated decay (-).
· Destruction of activated proteins by further proteolytic cleavage (-).
· Inhibition of activated proteases by inhibitor-complex formation (-).

Cascade mechanisms are illustrated in Fig. 4

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