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Life-Threatening Allergy An Homage to Von Pirquet

Mechanisms of Anaphylaxis

Richard F. Lockey, M.D.
Professor of Medicine, Pediatrics and Public Health
Director, Division of Allergy and Immunology
Joy McCann Culverhouse Chair in Allergy and Immunology
Department of Internal Medicine
University of South Florida College of Medicine
and James H. Haley Veterans’ Hospital

Dr. Lockey is Director of the Division of Allergy and Immunology and Professor of Medicine and Pediatrics, and Joy McCann Culverhouse Chair of Allergy and Immunology at the University of South Florida College of Medicine in Tampa, Florida. He is also Professor of Public Health at the University of South Florida School of Public Health and Chief of the Section of Allergy and Immunology at the James A. Haley Veterans’ Hospital. Dr. Lockey has authored, co-authored or edited over 500 scientific publications. He is Treasurer of the World Allergy Organization and is the current editor of the World Allergy Organization Web site and the Organization’s e-letter, WAO News and Notes. Among his many distinctions, Dr. Lockey is a Past-President of the American Academy of Allergy, Asthma and Immunology.


Anaphylaxis is a syndrome with varied mechanisms, clinical presentations, and severity and is an acute life-threatening reaction, mediated by an immunologic mechanism (allergic, IgE and non-IgE), but not always (non-allergic), that results from the sudden systemic release of mast cells and basophile mediators. These mediators result in some or all of the following signs and symptoms: diffuse erythema, pruritus, urticaria and/or angioedema, bronchospasm, laryngeal edema, hyperperistalsis, hypotension, and/or cardiac arrhythmias. Other symptoms can occur, such as nausea, vomiting, lightheadedness, headache, feeling of impending doom, uterine cramps, and unconsciousness. Usually reactions are uniphasic but also can be biphasic or prolonged.

IgE allergic mechanisms account for most anaphylaxis; however,non-IgE-mediated allergic anaphylaxis also occurs, such as with cytotoxic and immune complex reactions. The causes for non-allergic anaphylaxis, as occurs in radio contrast media reactions, remain unknown.

The end result is that when acute anaphylaxis occurs; it is potentially a life-threatening reaction. Understanding the allergic and non-allergic mechanisms which trigger anaphylaxis is important. So, too, is understanding the pathophysiologic consequences of these reactions in order to assure appropriate treatment and duration of treatment.


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