Allergen - Allergens are foreign substances that can be inhaled, touched, or eaten, which cause the body to produce substances that stimulate part of your immune system, causing an allergic reaction. Allergens cause the immune system to produce immunoglobulin E (IgE), which is an antibody that attaches to special cells in the lungs, gastrointestinal (GI) system, and bloodstream. With IgE attached, the cells produce the chemical substances that cause symptoms of allergy.
Allergic asthma - asthma that is triggered by allergies. When allergic asthma is one of the requirements for participation in a clinical trial, specific criteria are often used to document its presence. A "skin-pick" allergy test may be used. In this case, reactions to certain common allergens suggest the presence of allergic asthma. Some studies require the presence of a high level of IgE in the blood. IgE is a protein involved in the allergic response.
Allergic conjunctivitis - Allergic Conjunctivitis is the most common allergy affecting the eyes. The conjunctivae are the thin membranes covering the eyelids and the exposed surface of the eyes. This thin membrane is an active tissue of the immune system and responds to allergies caused by airborne particles, or other allergens. Allergic conjunctivitis occurs both seasonally and year-round (perennially). The seasonal allergic conjunctivitis is much more common, and is caused by exposure to airborne allergens, such as grass, tree and weed pollens and molds. The year-round form persists throughout the year and is caused by dust mites, animal dander (shed skin scales of furry animals) and feathers.
Allergic Reaction - When an allergen and an IgE antibody combine, cells release chemicals such as histamine and leukotrienes, which produce many of the familiar allergic symptoms such as runny nose, watery eyes, itching and sneezing. The leukotrienes, in particular, also cause inflammation and airway obstruction in asthma.
Allergic Rhinitis - Allergic rhinitis, also known as nasal allergy, or hay fever, is the most common allergic disorder. The incidence has increased in recent years. Asthma is prevalent in people with allergic rhinitis. Although only 3% to 5% of the general population has asthma, asthma affects 21% to 58% of patients diagnosed with allergies. Approximately 75% of children with asthma have significant allergies. An estimated 36 million people have allergic rhinitis.
There is strong evidence in the clinical literature supporting the relationship between asthma and allergic rhinitis. In 1993 estimated total cost associated with allergic rhinitis in the US was $34 billion. The symptoms of allergic rhinitis are runny nose, sneezing, and cough. Common triggers are pollen, dust, mold, and animal dander.
Allergy - An altered or heightened susceptibility to various foreign substances (allergens) that is harmful to the body. Allergies occur when a specific allergen (also known as antigen) combines with a specific IgE antibody. This combination produces chemicals that cause the symptoms of allergy as runny nose, watery eyes, itching and sneezing. A type of severe reaction is called "anaphylactic shock". It causes swelling of the body tissues (including the throat), vomiting, cramps, and a sudden drop in blood pressure. Anaphylaxis often occurs in persons particularly sensitive to penicillin or other medications, stinging insects, shellfish, or nuts.
Allergy Shots - The process involves repeated subcutaneous injections of specific allergen extracts. Previous allergy testing to determine which allergens cause a person's asthma is necessary, since the response to immunotherapy is specific to the allergen. After identification of a person's problematic allergens are determined, mixtures of extracts of those allergens can be prepared for injection.
Subcutaneous injections of dilute solutions of the allergen extracts are given one to two times a week to increase tolerance to one or more allergens so that natural exposure causes only mild or no symptoms. The allergen concentration is gradually increased to the person's maximum tolerated dose. Once the maximum tolerated dose (maintenance dose) is reached the interval between the injections is increased to once every two to four weeks. This regimen is continued for three to five years.
The role of specific immunotherapy in asthma management is under continual investigation. Currently available asthma medications and avoidance strategies usually provide good control of asthma. Specific immunotherapy, directed at treating the underlying allergy, may be considered when avoiding allergens is not possible or when appropriate medications fail to control asthma symptoms. Specific immunotherapy has been shown effective when grass and other pollen, domestic mites, or animal dander causes asthma.
Anaphylactic Reaction - Anaphylaxis is a sudden, severe, life-threatening and potentially fatal systemic allergic reaction. The reaction can involve several areas of the body such as the skin, respiratory tract, gastrointestinal tract and cardiovascular system. This rare reaction can occur within minutes to two hours after contact with the allergen (allergy-causing substance) such as an insect sting, a medication injection, during allergy testing, or after a particular food or medication has been taken by mouth. Anaphylactic reactions can be mild to life-threatening.
Anti-inflammatory Agents - Anti-inflammatory agents, such as cromolyn and nedocromil, corticosteroids, and leukotriene modifiers reduce the inflammation in the airways. Inflammation causes the bronchi (main branches leading from the throat to the lungs) to become hyper-reactive. A hyper-reactive airway is more sensitive to various asthma triggers such as exercise, cold air, smoke, cold viruses, and allergens. Anti-inflammatory medications usually are prescribed in the inhaled form. Possible side effects from inhaled anti-inflammatory medications include coughing and hoarseness
Antibodies - An antibody is a protein (called an immunoglobulin) that is made by the white blood cells (called lymphocytes) to defend against antigens and foreign substances. Pollens, dust mites, molds, foods, as well as bacteria, viruses and other microorganisms all contain antigens. The body produces antibodies as a necessary and protective response. In some people this protective response causes an inappropriate or over production of antibodies that can cause illness. The formation of an antibody called IgE causes hay fever, asthma or eczema when the person comes in contact with the substance (allergen) that caused the formation of that specific IgE antibody.
Anticholinergics - Anticholinergics are bronchodilators. These medications relax the smooth muscles of the bronchi and open up constricted airways. Anticholinergic bronchodilators used in COPD include ipratropium bromide (Atrovent®).
Antigen - An antigen is a substance that can stimulate the immune response to produce antibodies. This is an important part of the body's response against infection and disease. Antigens are foreign to the body. Allergens such as the proteins in pollens, spores, mold, and animal dander are special types of antigens that cause an IgE antibody response
Antihistamine - These medications block the effects of histamine. Histamine is released in response to an allergic reaction and is responsible for many allergy symptoms. Antihistamines decrease the itching, sneezing and runny nose that histamine causes in nose allergies. Antihistamines are the most popular drug for treating hay fever and are available both over-the-counter and by prescription, and are administered either by an oral tablet or topically as a nasal spray or eye drops.
Asthma Attack - Asthma attacks (flare-ups) are episodes of progressively worsening shortness of breath, cough, wheezing, difficult breathing, or chest tightness, or some combination of these symptoms. Attacks are also characterized by decreases in expiratory airflow (FEV1 or PEF) that can be demonstrated by measuring lung function using spirometers or peak flow meters. The severity of an acute asthma attack is often underestimated by patients and their relatives as well as by their health care professionals when early signs of worsening are not recognized, or if measurements of lung function are not used.
Severe attacks of asthma can be life threatening. Deterioration usually progresses over hours or days, but may occasionally occur over minutes. For this reason, patients and parents must know the action steps to take at the earliest sign of deterioration and before the attack requires emergency care or hospitalization.
Atopy - Atopy is the genetic tendency to develop the "classic" allergic diseases, which include: allergic rhinitis and conjunctivitis, asthma, and atopic dermatitis. Atopy is typically associated with a genetically determined capacity to develop IgE antibodies to common allergens, especially inhaled and food allergens. Atopy can be determined by skin test with specific allergens, also known as skin "prick tests." In many cases, especially in children and young adults, asthma is associated with atopy. Atopic diseases occur in families. The presence of atopy in persons with asthma increases the likelihood of others in the family developing asthma.