Adrenaline-induced platelet aggregation in patients with chronic urticaria and in patients with multiple drug intolerance.

It is now generally accepted that the beta-adrenergic system may play a role in the pathogenesis of allergic manifestations. One of the most interesting experimental models is the adrenaline induced platelet aggregation test, in which adrenaline selectively stimulates the beta-adrenergic receptors activating adenylcyclase. This test was considered as a model in the study of beta-receptor function in patients with allergic disorders. It therefore seemed worthwhile to submit two different groups of patients to this test, namely: a) Patients with chronic urticaria. Since in the large majority of cases no immunoallergic mechanism has been detected, various hypotheses have been proposed to explain its onset. b) Patients showing intolerance to several drugs: this is a large category of patients, predominantly females, presenting allergic-like reactions, mostly of the urticarioidangioedematous type, occurring following administration of various types of drugs. The investigation was performed on subjects of both sexes, grouped as follows: a) 33 patients with chronic urticaria. b) 31 patients with multiple drug intolerance. c) 28 normal volunteers (control subjects). From the results obtained it can be concluded that a tendency toward hyperagregation was more evident in patients with urticaria and less evident in those with multiple drug intolerance. The only finding of interest concerns the second aggregation wave, which was less frequent in patients with urticaria than in normal subjects, but the difference was not statistically significant. The adrenaline-induced platelet aggregation test does not appear to provide useful information on a deficit of beta-receptor function in the patients studied.