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Team:Brown/Project Introduction
From 2009.igem.org
The Allergic Response
The prevalence of food, seasonal, and other allergies has been rapidly increasing in recent times. In particular, over 50 million people in the United States suffer from allergic rhinitis, more commonly known as hay fever. This allergy is caused by allergens such as pollen or dust and causes the mucous membranes of the eyes and nose to become itchy and inflamed, resulting in irritating symptoms such as runny nose and watery eyes. Histamine has been identified as a principal mediator of inflammatory responses. Upon first contact with an allergen, plasma cells release Immunoglobulin E (IgE) antibodies. These antibodies then activate mast cell degranulation and release of histamine. When histamine reaches histamine receptors on various target cells, vasodilation and inflammation occurs, resulting in allergic symptoms.
Allergies are routinely treated with antihistamine drugs, which have many adverse effects. Antihistamines compete with histamine to bind and block these histamine receptors, preventing the initiation of the inflammatory response. However, antihistamines also block receptors of the nervous system, thereby causing drowsiness. For many people, sedation remains the primary concern when considering the adverse effects of the newer antihistamines, particularly since these drugs are given to patients with chronic disorders with treatment periods that often extend over several months or even years. Besides sedation, there also exists concern regarding the caridotoxicity of antihistamines and other adverse drug interactions. For patients suffering from chronic allergies and inflammation, there is a great need for an alternative strategy for combating allergic symptoms without causing significant side effects.
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Allergene presents a favorable alternative because it utilizes the binding affinity of a histamine binding protein isolated from a tick. Similar to antihistamines, this protein prevents histamine molecules from interacting with histamine. However, by directly sequestering the histamine molecules rather than blocking their receptors, the drowsiness side-effect is successfully avoided.
