immunology allergic disorders
Hereditary and Acquired Angioedema
Introduction
 deficiency) are caused by deficiency or dysfunction of complement 1 (C1) inhibitor, a protein involved in the regulation of the Complement activation , and of the kinin, clotting, and fibrinolytic pathways. The main symptom is swelling, often of the face, mouth, and upper airways, which can be severe; itching and urticaria do not occur. Diagnosis is by measurement of complement levels. (See also Overview of Allergic and Atopic Disorders , C1 inhibitordeficiency or dysfunction not only affects complement activation but also results in increased levels of bradykinin becauseC1 inhibitorinhibits activated kallikrein (required for the generation of bradykinin) in the kinin system pathway. The classical, lectin, and alternative pathways converge into a final common pathway when C3 convertase (C3 con) cleaves C3 into C3a and C3b. Ab=antibody; Ag=antigen; C1-INH=C1 inhibitor; MAC=membrane attack complex; MASP=MBL-associated serine protease; MBL=mannose-binding lectin. Overbar indicates activation. 