C1 inhibitor regulates OSCS-induced kallikrein activity.

(A) Normal human plasma, plasma depleted of C1 inhibitor, plasma depleted of factor XII, and plasma depleted of both C1 inhibitor and factor XII, were incubated with chondroitin sulfate A (CSA) or over sulfated chondroitin sulfate A (OSCS). The effect of kallikrein amidolytic activity was assessed by the addition of the s-2302 chromogenic substrate. (B) OSCS-induced kallikrein activity was totally inhibited by addition of 200 µg/ml of C1 inhibitor. At least three independent experiments were completed with duplicate samples for the assay.