Urticaria and angioedema.

Abstract

Urticaria may be the sole symptom of a minor reaction or it may be a manifestation of a progressive, fatal connective tissue or neoplastic disease. At least five basic pathogenetic pathways may initiate histamine release from mast cells. These are complement factors; chemical liberators; immunologic mechanisms; biologic, physical, and neurogenic factors; and general modifying phenomena. The interrelationship of these pathways has been shown, particularly stressing the potential significance of chemical liberators and complement-mediated events in several mechanisms. Implication that hormonal and neurohumoral substances may modify the entire mast-cell degranulating system has been entertained as important speculation awaiting confirmation. Diagnosis and therapy is discussed using these principles. In addition to a careful history and physical exam, determination of blood eosinophiles, total complement activity, quantitation of isolated complement components, selected skin tests, elimination regimes, and controlled provocative tests may be useful in individual cases. Although antihistamines constitute the principal means of therapy, their method of action impairs an early effect, and beta adrenergic amines must be given when shock or potentially fatal angioedema occur. Corticoids and immunosuppressive agents may be necessary for control in some of the serious underlying disorders. Three modes of experimental therapy are also discussed.