The \(C\bar 1\)-inactivator plays an important role not only in the initial phases of the complement system, but also in those of the coagulation, fibrinolysis and kinin systems. The present study was concerned with the reciprocal influence of decreased \(C\bar 1\)-inactivator levels in patients with hereditary angioneurotic edema (HANE, HAE). In 13 HANE-I patients there were significantly increased levels of the coagulation factors XII, XI, V, of plasminogen and of α-antiplasmin, while the factors IX and VII were decreased. Conversely, it emerged that in patients with markedly raised prephase factor levels, angioneurotic edema occurred in the presence of normal or only slightly decreased \(C\bar 1\)-inactivator levels. However, the ratio between factor XI and \(C\bar 1\)-INA activity was significantly higher than in normal and urticaria patients.
Factor XII, HMWK, XI, VIII and V levels were significantly raised in 10 patients with frank chronic urticaria, while factor VII was lowered. Numerous other factors and inhibitors of the coagulation, fibrinolysis and kinin systems were, however, normal or showed no significant differences.