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Physical Urticaria

 

The physical urticarias are a heterogeneous subgroup of chronic urticarias in which wheals can be reproducibly induced by different specific physical stimuli such as cold, heat, pressure, vibration, or sunlight.

Physical urticarias comprise up to 25 % of chronic urticarias and occur more frequently in young adults. Symptoms, i.e. wheal and flare responses or angioedema, are usually limited to the skin areas exposed to the eliciting stimulus. However, generalised urticaria with variable extracutaneous manifestations can also occur. Some patients may also present with more than one physical urticaria. Skin lesions in physical urticaria result from mast cell activation and mediator release. The mechanisms by which physical stimuli activate skin mast cells are not fully understood. Because of this, trigger avoidance and symptomatic treatment are key therapeutic concepts for physical urticarias. Identification of the inducing physical trigger, including its individual thresholds, is necessary for an effective therapy.

Here, we have summarized clinical features, diagnostic workup and therapy options for physical urticarias.

 

Molecular Approaches to Allergen Standardization

 

Molecular approaches to allergen standardization include the development of purified natural or recombinant allergen standards whose structural and allergenic properties have been validated, in tandem with certified immunoassays for allergen measurement. Purified allergens can be used individually or incorporated into multiple allergen standards.

Multicenter international collaborative studies are required to validate candidate allergen standards and immunoassays, as a prelude to being approved by regulatory agencies. Mass spectrometry is a sophisticated and powerful proteomics tool that is being developed for allergen analysis. Recent results using pollen allergens show that mass spectrometry can identify and measure specific allergens in a complex mixture and can provide precise information of the variability of natural allergen extracts. In future, the combined use of immunoassays and mass spectrometry will provide complete standardization of allergenic products.

Molecular standardization will form the basis of new allergy diagnostics and therapeutics, as well as assessment of environmental exposure, and will improve the quality of treatment options for allergic patients.

 

Urticaria: Attempts at Classification

 

Among the many attempts to classify urticaria, 2 categories have been accepted worldwide, namely according to time course into acute (shorter than 6 weeks) and chronic urticaria (longer than 6 weeks) and a classification according to etiopathophysiology.

A special subgroup is the physical urticarias where wheals are elicited via specific physical (mechanical, temperature, radiation) stimuli. In many forms of chronic urticaria, psychosomatic influences play a role. Despite great progress in modern immunology and allergology, chronic urticaria still remains a challenge for doctors and patients.

 

Anaphylaxis in Children: Current Understanding and Key Issues in Diagnosis and Treatment

 

Anaphylaxis is a severe allergic reaction that is rapid in onset and may cause death. Since it is unpredictable and potentially fatal, prompt recognition and treatment are vital to maximize a positive outcome.

The occurrence of anaphylaxis is increasing across all ages in the United States, with increased risk of worse outcome in teenagers/young adults and in those with comorbid conditions such as asthma. Gaps in the assessment of patient-specific risk factors, identification and prevention of triggers, recognition of signs/symptoms, and pharmacologic treatment of anaphylaxis have been identified at the physician and caregiver/patient level. A PubMed literature search (January 2000–December 2011) was conducted to identify publications on childhood anaphylaxis using the following terms: food allergy, food allergens, food hypersensitivity, epinephrine, epinephrine auto-injectors, anaphylactic triggers, and anaphylaxis.

This review will critically appraise these key issues and highlight strategies that might result in improved management of anaphylaxis in children.

 

The Pathologic and Clinical Intersection of Atopic and Autoimmune Disease

Hypersensitivity reactions of the immune system have been broadly categorized into the atopic and autoimmune depending on whether the antigen triggering the reaction is endogenous (or self) or exogenous, the types of cellular and humoral components involved, and the clinical symptoms.

Research into the pathophysiology of the resultant disease states has focused on a dichotomy between Th1 and Th2 T helper lymphocytes thought to govern autoimmune and atopic disease, respectively. Recent discoveries, however, have served to dispute this paradigm and have provided additional insight into the roles of Th17 cells, B-lymphocytes and T regulatory cells as well as the considerable communication and commonalities between the complex signaling pathways. Furthermore, clinical studies have served to challenge the idea that the presence of atopy and autoimmunity are mutually exclusive states.

Finally, application of recent approaches to treatment—biologic targeted therapy in autoimmunity and induction of immune tolerance in atopic disease—to both disease states have shown mixed but promising results.

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