Pathophysiology of Chronic Urticaria

Abstract

Chronic urticaria includes several different subsets with distinct pathophysiologies, and with important implications for investigation and treatment. Chronic ‘idiopathic’ urticaria represents a special challenge, which, until recently, was not taken up by dermatological or immunological investigators. However, it has now emerged that at least 30% of patients possess histamine-releasing autoantibodies against FcΕR1, or less commonly IgE itself. These autoantibodies are causative. Recent work implicates complement activation in most cases. Functional (i.e. histamine releasing) autoantibodies are specific to chronic urticaria. However, immunoreactive (non-histamine-releasing) anti-FcΕR1 autoantibodies can be found in sera of patients with physical urticarias and with autoimmune connective tissue and bullous diseases. The reason for the occurrence of this disease type in some individuals but not others is unclear. One possibility is the development, in genetically predisposed persons, of autoantibodies by molecular mimicry – perhaps against lipopolysaccharide of Helicobacter pylori, an organism frequently infecting the upper gastrointestinal tract of chronic urticaria patients.

Clinical and Laboratory Examinations in the Subgroups of Chronic Urticaria

“…The aetiology of chronic urticaria is heterogeneous [1, 2]. In some cases, urticaria may develop on a pseudoallergic or focal infection-related basis, while the aetiological role of real food allergy is minimal in chronic urticaria [3].…”

Skin Prick Tests in Patients with Chronic Urticaria

“…According to experimental results, the mast (14)(15). Besides the immune triggering reactions, many other substances and factors may cause a non specific activation of the mast and basophil cells and the release of vasoactive mediators, underlining the complexity of mechanisms that cause urt icaria and exp laining many types of urticaria caused by natural factors, medicines and radiopaque substances (5,13,(16)(17) .…”

“…A number of mechanisms have been implicated in the manifestation of urticaria (2)(3). However, in the majority of patients (60-70%) no specific cause of urticaria can be found (3)(4)(5). The mast cell secretory products (histamine, bradykinin, tryptase etc), are thought to be the agents for producing urticaria lesions and urticaria clinical manifestations (3,5,6).…”

“…However, in the majority of patients (60-70%) no specific cause of urticaria can be found (3)(4)(5). The mast cell secretory products (histamine, bradykinin, tryptase etc), are thought to be the agents for producing urticaria lesions and urticaria clinical manifestations (3,5,6). In vitro and in vivo tests aimed at establishing the generative causes for urticaria have proven of a rather limited value, more so in chronic urticaria.…”

Estudo da qualidade de vida nos pacientes com urticária crônica

“…3,4 The condition is considered chronic when wheals are present on a daily or almost daily basis for a period exceeding six weeks. 1,2,[5][6][7] In this form, the disease often interferes with the patient's routine activities, damaging his/her self-esteem and negatively affecting interpersonal relationships. 6,8 Since the course of the disease is benign from a clinical point of view and it is non-life threatening, with transitory lesions and temporary disfigurement, healthcare professionals often underestimate the impact of chronic urticaria on patients' quality of life.…”