Contact system activation and bradykinin generation in patients with idiopathic angioedema

PATIENTS AND METHODS PatientsWe studied 9 patients with idiopathic angioedema (4 men and 5 women; age range: 32-83 years), during acute angioedema attacks.All patients presented to the emergency department of Ospedale Maggiore of Crema for angioedema reporting previous episodes of angioedema not responding to antihistamine, no family history or known causes of angioedema and no therapy with ACE inhibitors or non-steroidal anti-inflammatory drugs.Thus, they can be considered affected with idiopathic nonhistaminergic acquired angioedema.Exclusion criteria were age less than 18 years and presence of severe comorbidities.The study was approved by Ethics Committee Valpadana of ASST Ospedale Maggiore Crema (No. 104, 22 march 2019) and was carried out in conformity with the 2013 revision of the Declaration of Helsinki and the code of Good Clinical Practice.All patients gave their written consent to participate in the study.Blood was collected before any treatment from antecubital veins with minimal stasis using specific anticoagulant mixtures to avoid in vitro activation of the contact system as well as generation and degradation of vasoactive mediators [9][10][11].Blood samples were immediately centrifuged and the plasma was frozen, as described below.Nine healthy subjects, sex-and age-matched with patients, served as controls.Control subjects were staff members of the hospital or their relatives, and their blood samples were obtained in the emergency department and processed with the same method used for patients.