Pathogenesis of Physical Induced Urticarial Syndromes

Urticaria is a common skin disorder that is classified according to its chronicity into acute and chronic forms. It may occur spontaneously or on exposure to a physical factor. In the latter case, the urticaria is classified as a physical urticaria . Physical urticaria may be induced by mechanical and applied pressure, exercise, or exposure to cold, heat, sun, water, or vibration. The urticarial lesions are generally thought to be the result of mast cell activation and degranulation, which is supported by the finding of increased levels of serum histamine during some urticarial flares. Passive transfer experiments, whereupon serum from affected donors is transferred into recipient s skin followed by physical stimulation with resultant urticaria at the site of challenge, have been positive in some instances. This suggests the presence of an intrinsic factor in serum, such as IgE, which then mediates activation of tissue mast cells. However, the pathogenesis in general remains unclear and a genetic basis for these disorders has not been elucidated. The goal of this protocol is thus to gain a better understanding of the pathogenesis of physical urticaria through the investigation of subjects with severe and unusual phenotypes and/or inherited patterns of disease. Subjects will undergo a clinical evaluation that will include verification of their urticaria. Blood and tissue samples, if available, will be collected for analysis. The analysis will be targeted toward the determination of novel serum mediators, mast cell activation and mutational analysis in families with inherited patterns.