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Allergy - Diagnosis And Treatment

allergic allergen blood mast

The patient's medical history provides the primary basis for the diagnosis of allergies. Skin patch tests are sometimes used to determine exactly which potential allergens can produce a reaction in the patient. A group of substances are placed in patches under the skin; any actual allergen will raise a weal (a red, circular swelling) at the site of the patch. The weal is a circular area of swelling that itches and is reddened. The tests at times produce false positives, so that they cannot be relied on exclusively.

The simplest form of treatment is the avoidance of the allergic substance, but that is not always possible. In such cases, desensitization to the allergen is sometimes attempted by exposing the patient to slight amounts of the allergen at regular intervals.

Antihistamines, which are now prescribed and sold over the counter as a rhinitis remedy, were discovered in the 1940s. There are a number of different ones, and they either inhibit the production of histamine or block them at receptor sites. After the administration of antihistamines, IgE receptor sites on the mast cells are blocked, thereby preventing the release of the histamines that cause the allergic reactions. The allergens are still there, but the body's "protective" actions are suspended for the period of time that the antihistamines are active. Antihistamines also constrict the smaller blood vessels and capillaries, thereby removing excess fluids. Recent research has identified specific receptor sites on the mast cells for the IgE. This knowledge makes it possible to develop medicines that will be more effective in reducing the symptoms of various allergies.

Corticosteroids are sometimes prescribed to allergy sufferers as anti-inflammatories. Decongestants can also bring relief, but these can be used for a short time only, since their continued use can set up a rebound effect and intensify the allergic reaction.

Resources

Books

Adelman, Daniel C., and Thomas B. Casale. Manual of Allergy and Immunology: Diagnosis and Therapy. 4th ed. Philadelphia: Lippincott Williams & Wilkins Publishers, 2002.

Joneja, Janice Vickerstaff, and Leonard Bielory. Understanding Allergy, Sensitivity, & Immunity. New Brunswick, NJ: Rutgers University Press, 1990.

Steinman, Marion. A Parent's Guide to Allergies and Asthma. New York: Dell Publishing, 1992.


Organizations

American College of Allergy, Asthma & Immunology, 85 West Algonquin Rd., Suite 550, Arlington Heights, IL 60005. 1–800–842–7777. <http://allergy.mcg.edu> (October 19, 2002).


Other

National Institutes of Health. "The National Institue of Allergy and Infectious Diseases" <http://www.niaid.nih.gov/default.htm> (October 19, 2002).


Jordan P. Richman

KEY TERMS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Allergen

—An otherwise harmless substance that can cause a hypersensitive allergic response.

Anaphylactic shock

—A violent, sometimes fatal, response to an allergen after initial contact.

Corticosteroids

—Drugs that stimulate the adrenal gland and are highly effective in treating asthma and allergies but also have many side effects.

Decongestants

—Drugs used for a short term to reduce mucous membrane congestion.

Histamines

—A chemical released from cells in the immune system as part of an allergic reaction.

IgE

—The chief immunoglobulin responsible for producing the compounds that cause allergic reactions.

Lymphocyte

—A white blood cell that stimulates antibody formation.

Mast cell

—A tissue white blood cell located at the site of small blood vessels.

Receptor sites

—Places on the mast cell where Y-shaped antibodies stimulate histamine production.

Rhinitis

—The common condition of upper respiratory tract inflammation occurring in both colds and allergy.

Weal

—The reddened, itchy swelling caused by a skin patch test.

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