The Asthma Allergy Connection
By editor | February 6, 2008
The link between allergies and asthma is very strong. Most children with asthma-probably as many as 80 percent have allergies, and 40 percent of children with allergies in the nose (hay fever or allergic rhinitis, for example) also have asthma symptoms.
The key point is this: if you can control children’s allergies, their asthma symptoms will be less intense and less frequent. To understand and manage asthma successfully, it’s important to know something about allergies.
How Do Allergies Occur
Allergies are a common problem that affects at least two of every ten Americans. Simply put, people with allergies react to certain substances called allergens-dust, pollen, animal dander, mold, or smoke, for example-that don’t cause reactions in other people. An allergic person’s immune system responds to allergens like a false alarm. When an allergen triggers the immune system setting off the alarm the body reacts by sneezing, wheezing, coughing, and/or itching, depending on what particular part of the body has the reaction. Other allergens in foods cause a skin or intestinal reaction.
A quick biology lesson: our bodies make immunoglobulins to help fight various infections. There are five different types of immunoglobulin: IgG, IgA, IgM, IgE, and IgD. IgG, IgA, and IgM are some of the body’s most important weapons against bacterial infections. The allergic antibody called IgE (immunoglobulin E) is part of the body’s natural response for fighting other types of infections, particularly parasites like worms. In some one with allergies, the body recognizes certain allergens as foreign invaders and makes more IgE. Everyone makes some 1gE, but allergic children make more IgE in reaction to pollen and dust than a nonallergic child does.
An allergic reaction starts when an allergen attaches to the allergen-specific-IgE antibody and activates certain cells, including “mast cells” found in skin and tissues that line the nose, throat, and lungs. An IgE antibody that attaches to a mast cell acts like a fuse on a bomb. When IgE antibody’s specific allergen comes along, it’s like touching a match to the fuse the antibody makes the mast cell burst open and release a number of substances, including one called histamine that causes redness, swelling, and itching.
Location is everything. The site where histamine is released determines the type of reaction. When histamine is released in the tissues lining the nose, the results are redness, itching, swelling, sneezing, and a runny nose what allergists call allergic rhinitis, but most people simply call it hay fever. When histamine is released in the skin, the results are itching, rashes, and hives causing atopic dermatitis, or eczema. When histamine is released in the stomach, it causes cramping and diarrhea. When histamine is released in the lungs, it causes airways to tighten, swell up, and produce extra mucus-the recipe for asthma.
To develop an allergy, a child needs to be exposed to the allergen several times. The first few exposures cause the immune system to make more 1gE. Subsequent exposures will cause the body to respond to the IgE and allergen by releasing histamine, and then symptoms will appear.
This is why many children do not have allergy symptoms in the first few years of life but develop them during their school-age years or later.
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