Protease inhibitors in plasma of patients with chronic urticaria.

The hypothesis that deficiencies of plasma protease inhibitors might play a role in the pathogenesis of chronic urticaria was evaluated. Plasma levels were measured in patients with urticaria and a matched control group for alpha1-antitrypsin, alpha2-macroglobulin, total trypsin-inhibiting capacity, kallikrein-inhibiting capacity, and the complement factors C1 esterase inhibitor, C3, and C4. A total of 92 patients with chronic urticaria or more than three months' duration was studied. Patients with acquired cold urticaria had significantly decreased levels of alpha1-antitrypsin and total antitrypsin activity. In patients with acquired angioneurotic edema, alpha1-antitrypsin levels and antichymotrypsin activities were lowered, with less significant decreases in anti-trypsin and antikallikrein activities. Levels of C1 esterase inhibitor , C3, and C4 were normal in all groups. There was no correlation between the increased sensitivity to intracutaneously administered kallikrein injection and deficiencies of of protease inhibitors.