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 α1-antitrypsin, α2-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 of more than three months' duration was studied. Patients with acquired cold urticaria had significantly decreased levels of α1-antitrypsin and total antitrypsin activity. In patients with acquired angioneurotic edema, α1-antitrypsin levels and antichymotrypsin activities were lowered, with less significant decreases in antitrypsin 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 protease inhibitors.
Doeglas HMG, Bleumink E. Protease Inhibitors in Plasma of Patients With Chronic Urticaria. Arch Dermatol. 1975;111(8):979-985. doi:10.1001/archderm.1975.01630200039001