An allergy is an abnormal reaction to an ordinarily harmless substance called an allergen. When an allergen, such as pollen, is absorbed into the body of an allergic person, that person's immune system views the allergen as an invader and a chain reaction is initiated. White blood cells of the immune system produce IgE antibodies. These antibodies attach themselves to special cells called mast cells, causing a release of potent chemicals such as histamine. These chemicals cause symptoms such as a runny nose, watery eyes, itching and sneezing.
Hundreds or even thousands of ordinary substances can trigger allergic reactions. These are called "allergens." Among the most common are plant pollens, molds, household dust (dust mites), animal dander, foods, medicines and insect stings.
An allergic reaction may occur anywhere in the body, but usually appears in the skin, eyes, lining of the stomach, nose, sinuses, throat and lungs -- places where special immune system cells are stationed to fight off invaders that are inhaled, swallowed or come in contact with the skin.
Allergies can affect anyone, regardless of age, gender, race or socioeconomic status. While it's true that allergies are more common in children, they can occur for the first time at any age or, in some cases, recur after many years of remission.
Although the exact genetic factors are not yet understood, the tendency to allergies, as well as to allergic disease, is linked to heredity.
Immunotherapy involves the injection or oral drops of allergenic extracts (tiny amounts of allergens) that are given over a period of 3-5 years. By gradually increasing the amount of extract, tolerance to the offending allergen will increase, and the patient's symptoms will be relieved.
Regularly scheduled, repeated exposure to small amounts of an allergen can lead to immunity, whereas infrequent and erratic exposure does not confer immunity but increases the likelihood of producing allergen sensitization.
Irregular exposure to allergens can lead to the production of antibodies (called IgE-mediated antibodies). The presence of these antibodies, when exposed to an allergen can lead to an allergic reaction.
In allergy shots or allergy drops, the allergen exposure is closely regulated and given on a scheduled basis. This leads to the production of blocking antibodies (called IgG antibodies) and a decrease in the level of allergic or IgE-mediated antibodies.
The information provided on the Advanced ENT Denver site is for informational purposes only and should not be treated as medical or healthcare advice. Nothing contained on the Advanced ENT Denver site is intended to be used for medical diagnosis or treatment or as a substitute for consultation with a qualified health professional.
