Something in the air: airborne allergens.

When is sneezing not a symptom of a cold? Very often, when it represents an allergic reaction to something in the air. It is estimated that 35 million Americans suffer from upper respiratory allergic reactions to airborne pollen. Pollen allergy, commonly called hay fever, is one of the most common chronic diseases in the United States. Worldwide, airborne dust causes the most problems for people with allergies. The respiratory symptoms of asthma, which affects approximately 15 million Americans, are often provoked by airborne allergens (substances that cause an allergic reaction).

Allergic diseases are among the major causes of illness and disability in the United States, affecting as many as 40 to 50 million Americans. The National Institute of Allergy and Infectious Diseases, a component of the National Institutes of Health, conducts and supports research on allergic diseases. The goals of this research are to provide a better understanding of the cause of allergy, to improve the methods for diagnosing and treating allergic reactions, and eventually to prevent allergies. This booklet summarizes what is known about the causes and symptoms of allergic reactions to airborne allergens, how these reactions are diagnosed and treated, and what medical researchers are doing to help people who suffer from these allergies.

What is an allergy?

An allergy is a specific immunologic reaction to a normally harmless substance, one that does not bother most people. Allergic people often are sensitive to more than one substance. Types of allergens that cause allergic reactions include food, dust particles, medicines, insect venom, mold spores, or pollen. Why are some people allergic to these substances while others are not?

Scientists think that people inherit a tendency to be allergic, although not to any specific allergen. Children are much more likely to develop allergies if their parents have allergies. Even if only one parent is allergic, a child has a one in four chance of developing allergies. Exposure to allergens at certain times when the body's defenses are lowered or weakened, such as after a viral infection, during puberty, or during pregnancy, seems to contribute to the development of allergies.

What is an allergic reaction?

Normally, the immune system functions as the body's defense against invading agents such as bacteria and viruses. In most allergic reactions, however, the immune system is responding to a false alarm. When allergic persons first come into contact with an allergen, their immune systems treat the allergen as an invader and mobilize to attack. The immune system does this by generating large amounts of a type of antibody (a disease-fighting protein) called immunoglobulin E, or IgE. Only small amounts of IgE are produced in nonallergic people. Each IgE antibody is specific for one particular allergenic  (allergy-producing) substance. In the case of pollen allergy, the antibody is specific for each type of pollen: one antibody may be produced to react against oak pollen and another against ragweed pollen, for example.

These IgE molecules attach themselves to the body's mast cells, which are tissue cells, and to basophils, which are blood cells. When the allergen next encounters the IgE, it attaches to the antibody like a key fitting into a lock, signaling the cell to which the IgE is attached to release (and in some cases to produce) powerful inflammatory chemicals like histamine, prostaglandins, and leukotrienes. These chemicals move into various parts of the body, such as the respiratory system, and cause the symptoms of allergy. Some people with allergy develop asthma. The symptoms of asthma include coughing, wheezing, and shortness of breath due to a narrowing of the bronchial passages (airways) in the lungs and to excess mucus production. Asthma can be disabling and sometimes can be fatal. If wheezing and shortness of breath accompany allergy symptoms, it is a signal that the bronchial tubes also have become involved, indicating the need for medical attention.

Symptoms of Allergies to Airborne Substances

The signs and symptoms are familiar to many:

* Sneezing often accompanied by a runny or clogged nose

* Coughing and postnasal drip

* Itching eyes, nose, and throat

* Allergic shiners (dark circles under the eyes caused by increased blood flow near the sinuses)

* The "allergic salute" (in a child, persistent upward rubbing of the nose that causes a crease mark on the nose)

* Watering eyes

* Conjunctivitis (an inflammation of the membrane that lines the eyelids, causing red-rimmed, swollen eyes and crusting of the eyelids).

In people who are not allergic, the mucus in the nasal passages simply moves foreign particles to the throat, where they are swallowed or coughed out. But something different happens to a person who is sensitive to airborne allergens.

As soon as the allergen lands on the mucous membranes lining the inside of the nose, a chain reaction occurs that leads the mast cells in these tissues to release histamine. This powerful chemical enlarges the many small blood vessels  in the nose. Fluids escape through these expanded vessel walls, which causes the nasal passages to swell, resulting in nasal congestion.

Histamine can also cause sneezing, itching, irritation, and excess mucus production, which can result in allergic rhinitis (funny nose). Other chemicals made and released by mast cells, including prostaglandins and leukotrienes, also contribute to allergic symptoms.

Pollen Allergy

Each spring, summer, and fall tiny particles are released from trees, weeds, anti grasses. These particles, known as pollen, hitch rides on currents of air. Although their mission is to fertilize parts of other plants, many never reach their targets. Instead, they enter human noses and throats, triggering a type of seasonal allergic rhinitis called pollen allergy, which many people know as hay fever or rose fever (depending on the season in which the symptoms occur).

Of all the things that can cause an allergy, pollen is one of the most widespread. Many of the foods, drugs, or animals that cause allergies can be avoided to a great extent; even insects and household dust are escapable. Short of staying indoors when the pollen count is high--and even that may not help-there is no easy way to evade windborne pollen.

People with pollen allergies often develop sensitivities to other

troublemakers that are present all year, such as dust. For these allergy sufferers, the "sneezin" season" has no limit. Year-round airborne allergens cause perennial allergic rhinitis, as distinguished from seasonal allergic rhinitis.

What is pollen?

Plants produce microscopic round or oval pollen grains to reproduce. In some species, the plant uses the pollen from its own flowers to fertilize itself. Other types must be cross-pollinated; that is. in order for fertilization to take place and seeds to form, pollen must be transferred from the flower of one plant to that of another plant of the same species. Insects do this job for certain flowering plants, while other plants rely on wind transport.

The types of pollen that most commonly cause allergic reactions are produced by the plain-looking plants (trees, grasses, and weeds) that do not have showy  flowers. These plants manufacture small, light, dry pollen granules that are custom-made for wind transport. Samples of ragweed pollen have been collected 400 miles out at sea and 2 miles high in the air. Because airborne pollen is carried for long distances, it does little good to rid an area of an offending plant--the pollen can drift in from many miles away. In addition, most allergenic pollen comes from plants that produce it in huge quantities. A single ragweed plant can generate a million grains of pollen a day.

The chemical makeup of pollen is the basic factor that determines whether it is likely to cause hay fever. For example, pine tree pollen is produced in large amounts by a common tree, which would make it a good candidate for causing allergy. The chemical composition of pine pollen, however, appears to make it less allergenic than other types. Because pine pollen is heavy, it tends to fall straight down and does not scatter. Therefore, it rarely reaches human noses.

Among North American plants, weeds are the most prolific producers of allergenic pollen. Ragweed is the major culprit, but others of importance are sagebrush, redroot pigweed, lamb's quarters. Russian thistle (tumbleweed), and English plantain. Grasses and trees, too, are important sources of allergenic pollens. Although more than 1,000 species of grass grow in North America, only a few produce highly allergenic pollen. These include timothy, Johnson, Bermuda, redtop, orchard, sweet vernal, and Kentucky bluegrass. Trees that produce allergenic pollen include oak, ash, elm. hickory, pecan, box eider, and mountain cedar.

It is common to hear people say that they are allergic to colorful or scented flowers like roses. In fact, only florists, gardeners and others who have prolonged, close contact with flowers are likely to become sensitized to pollen from these plants. Most people have little contact with the large, heavy, waxy pollen grains of many flowering plants because this type of pollen is not carried by wind but by insects such as butterflies and bees.

When do plants make pollen?

One of the most obvious features of pollen allergy is its seasonal nature-people experience its symptoms only when the pollen grains to which they are allergic are in the air. Each plant has a pollinating period that is more or less the same from year to year. Exactly when a plant starts to pollinate  seems to depend on the relative length of night and day-and therefore on geographical location-rather than on the weather. (On the other hand, weather conditions during pollination can affect the amount of pollen produced and distributed in a specific year.) Thus, the farther north you go, the later the pollinating period and the later the allergy season.

A pollen count, which is familiar to many people from local weather reports, is a measure of how much pollen is in the air. This count represents the concentration of all the pollen (or of one particular type, like ragweed) in the air in a certain area at a specific time. It is expressed in grains of pollen per square meter of air collected over 24 hours. Pollen counts tend to be highest early in the morning on warm, dry, breezy days and lowest during chilly, wet periods. Although a pollen count is an approximate and fluctuating measure, it is useful as a general guide for when it is advisable to stay indoors and avoid contact with the pollen.

Mold Allergy

Along with pollens from trees, grasses, and weeds, molds are an important cause of seasonal allergic rhinitis. People allergic to molds may have symptoms from spring to late fall. The mold season often peaks from July to late summer. Unlike pollens, molds may persist after the first killing frost. Some can grow at subfreezing temperatures, but most become dormant. Snow cover lowers the outdoor mold count drastically but does not kill molds. After the spring thaw, molds thrive on the vegetation that has been killed by the winter cold. In the warmest areas of the

United States, however, molds thrive all year and can cause year- round (perennial) allergic problems. In addition. molds growing indoors can cause perennial allergic rhinitis even in the coldest climates.

What is mold?

There are thousands of types of molds and yeast, the two goups of plants in the fungus family. Yeasts are single cells that divide to form clusters. Molds consist of many cells that grow as branching threads called hyphae. Although both groups can probably cause allergic reactions, only a small number of molds are widely recognized offenders.

The seeds or reproductive particles of fungi are called spores. They differ in size, shape, and color among species. Each spore that germinates can give rise to new mold growth, which in turn can produce millions of spores. What is mold allergy?

When inhaled, microscopic fungal spores or, sometimes, fragments of fungi may cause allergic rhiniris. Because they are so small. mold spores may evade the protective mechanisms of the nose and upper respiratory tract to reach the lungs and bring on asthma symptoms. Build-up of mucus, wheezing, and difficulty in breathing are the result. Less frequently, exposure to spores or fragments may lead to a lung disease known as hypersensitivity pneumonitis, which will be discussed later.

In a small number of people, symptoms of mold allergy may be brought on or worsened by eating certain foods, such as cheeses, processed with fungi. Occasionally, mushrooms, dried fruits, and foods containing year, soy sauce, or vinegar will produce allergic symptoms. There is no known relationship, however, between a respiratory allergy to the mold Penicillum and an allergy to the drug penicillin, made from the mold.

Where do molds grow?

Molds can be found wherever there is moisture, oxygen, and a source of the few other chemicals they need. In the fall they grow on rotting logs and fallen leaves, especially in moist, shady areas. In gardens, they can be found in compost piles and on certain grasses and weeds. Some molds attach to grains such as wheat, oats, barley, and corn, making farms, grain bins, and silos likely places to find mold.

Hot spots of mold growth in the home include damp basements and closets, bathrooms (especially shower stalls), places where fresh food is stored, refrigerator drip trays, house plants, air conditioners, humidifiers, garbage pails, mattresses, upholstered furniture, and old foam rubber pillows.

Bakeries, breweries, barns, dairies, and greenhouses are favorite places for molds to grow. Loggers, mill workers, carpenters, furniture repairers, and upholsterers often work in moldy environments.

Which molds are allergenic?

Like pollens, mold spores are important airborne allergens only if they are abundant, easily carried by air currents, and allergenic in their chemical makeup. Found almost everywhere, mold spores in some areas are so numerous they often outnumber the pollens in the air. Fortunately, however, only a few dozen different types are significant allergens.

In general, Alternaria and Cladosporium (Hormodendram) are the molds most commonly found both indoors and outdoors throughout the United States. Aspergillus, Penicillium. Helminthosporium, Epicoccum, Fusarium, Mucor, Rhizopus, and Aureobasidium (Pullularia) are also common.

Are mold counts helpful?

Similar to pollen counts, mold counts may suggest the types and relative quantities of fungi present at a certain time and place. For several reasons, however, these counts probably cannot be used as a constant guide for daily activities. One reason is that the number and types of spores actually present in the mold count may have changed considerably in 24 hours because weather and spore dispersal are directly related. Many of the common allergenic molds are of the dry spore type-they release their spores during dry, windy weather.

Other fungi need high humidity, fog, or dew to release their spores. Although rain washes many larger spores out of the air, it also causes some smaller spores to be shot into the air.

In addition to the effect of day-to-day weather changes on mold counts, spore populations may also differ between day and night. Day favors dispersal by dry spore types and night favors wet spore types.

Are there other mold-related disorders?

Fungi or microorganisms related to them may cause other health problems similar to allergy. Some kinds of Aspergillus especially may cause several different illnesses, including both infections and allergy. These fungi may lodge in the airways or a distant part of the lung and grow until they form a compact sphere known as a "fungus ball." In people with lung damage or serious underlying illnesses, Asperillus may grasp the opportunity to invade and actually infect the lungs or the whole body.

In some individuals, exposure to these fungi can also lead to asthma or to an illness known as "allergic bronchopulmonary aspergillosis." This latter condition, which occurs occasionally in people with asthma, is characterized by wheezing, low-grade fever, and coughing up of brown-flecked masses or mucous plugs. Skin testing, blood tests, x-rays, and examination of the sputum for fungi can help establish the diagnosis. Corticosteroid drugs are usually effective in treating this reaction; immunotherapy (allergy shots) is not helpful. The occurrence of allergic aspergillosis suggests that other fungi might cause similar respiratory conditions.

Inhalation of spores from fungus-like bacteria. called actinomycetes, and from molds can cause a lung disease called hypersensitivity pneumonitis. This condition is often associated with specific occupations. For example, farmer's lung disease results from inhaling spores growing in moldy hay and gains in silos. Occasionally, hypersensitivity pneumonitis develops in people who live or work where an air conditioning or a humidifying unit is contaminated with and emits these spores.

The symptoms of hypersensitivity pneumonitis may resemble those of a bacterial or vital infection such as the flu. Bouts of chills, fever, weakness, muscle pains, cough, and sh6rtness of breath develop 4 to 8 hours after exposure to the offending organism. The symptoms gradually disappear when the source of exposure is removed. If this is not possible, such as in occupational settings, it may be necessary to increase the ventilation of the workplace, wear a mask with a filter capable of removing spores, or change jobs. If hypersensitivity pneumonitis is allowed to progress, it can lead to serious heart and lung problems.

Dust Allergy

An allergy to dust found in houses is perhaps the most common cause of perennial allergic rhiniris. House dust allergy usually produces symptoms similar to pollen allergy.

Rather than a single substance, house dust is a varied mixture of potentially allergenic materials. It may contain fibers from different types of fabrics; cotton lint, feathers, and other stuffing materials; bacteria; mold and fungus spores (especially in damp area); food particles; bits of plants and insects; and other allergens peculiar to an individual home.

Dust also may contain microscopic mites. These mites, which also live in bedding, upholstered furniture, and carpets, thrive in summer and die in winter. However, in a warm, humid house, they continue to thrive even in the coldest months. The particles seen floating in a shaft of sunlight are dead dust mites and their waste-products. These waste-products, which are proteins, actually provoke the allergic reaction. House dust mite allergy is the major year-round allergy in the world, though ragweed allergy is more prevalent in the United States.

Waste-products of cockroaches are also an important cause of allergy symptoms from household allergens, particularly in some urban areas of the United States.

Animal Allergy

Household pets are the main culprits in causing allergic reactions to animals. It was once thought that pet allergy was provoked by dander or fur from cats and dogs. Now, however, the allergen is known to be proteins in the saliva that is present on the dander or fur. Cats win the prize for causing the most allergic reactions. One reason may be that cats preen themselves more than other furry pets. This preening coats the hairs with saliva containing allergens, which become airborne. when the saliva dries. Also, it may be because cats are held more and often spend more time in the house, close to humans, than do dogs. Some rodents, such as guinea pigs and gerbils, have become increasingly popular as household pets. They, too, can cause allergic reactions in some people. Urine is the major source of allergens from these animals.

Allergies to animals can take 2 years or more to develop and may not subside until 6 months or more after ending contact with the animal. Carpet and furniture are a reservoir for pet allergens, and the allergens can remain in them for 4 to 6 weeks. In addition, these allergens can stay in household air for months after the animal has been removed. Therefore, it is wise for people with an animal allergy to check with the landlord or previous owner to find out if furry pets had lived previously on the premises.

Chemical Sensitivity

"Allergic to the twentieth century" is a phrase that has been used to describe people who seem to react to everything in their environment-indoors and outdoors. These allergy-like reactions can result from exposure to man-made substances, such as those found in paints or carpeting, or to natural substances, such as odors emitted by plants and flowers. Although the symptoms may resemble some of the manifestations of true allergies, sensitivity to chemicals does not represent a true allergic reaction.

Diagnosing Allergic Diseases

People with allergy symptoms, such as allergic rhinitis, may at first suspect they have a cold--but the "cold" lingers on. It is important to see a doctor about any respiratory illness that lasts longer than a week or two. When it appears that the symptoms are caused by an allergy, the patient should see a physician who understands the diagnosis and treatment of allergies. If the patient's medical history indicates that the symptoms recur at the same time each year, the physician will work under the theory that a seasonal allergen (like pollen) is involved. Properly trained specialists recognize the patterns of the local seasons and the association between these patterns and symptoms. The medical history suggests which allergens are the likely culprits. The doctor will also examine the mucous membranes, which often appear swollen and pale or bluish in persons with allergic conditions.

Skin Tests

To confirm which allergen is responsible, skin testing may be recommended using extracts from allergens such as dust, pollens, or molds commonly found in the local area. A diluted extract of each kind of allergen is injected under the patient's skin or is applied to a scratch or puncture made on the patient's arm or back.

With a positive reaction, a small, raised, reddened area with a surrounding flush (called a wheal and flare) will appear at the test site. The size of the wheal can provide the physician with an important diagnostic clue, but a positive reaction does not prove that a particular pollen is the cause of a patient's symptoms. Although such a reaction indicates that IgE antibody to a specific allergen is present in the skin, respiratory symptoms do not necessarily result.

Blood Tests

Skin testing is not advisable in some people such as those with widespread skin conditions like eczema. Diagnostic tests can be done using a blood sample from the patient to detect levels of IgE antibody to a particular allergen. One such blood test is called the PAST (radioallergosorbent test), which can be performed when eczema is present or if a patient has taken medications that interfere with skin testing.

It is expensive to perform, takes several weeks to yield results, and is somewhat less sensitive than skin testing. Overall, skin testing is the most sensitive and least costly diagnostic tool. Treating Allergic Diseases

There are three general approaches to the treatment of these allergies: avoidance of the allergen, medication to relieve symptoms, and allergy shots. Although no cure for allergies has yet been found, one of these strategies or a combination of them can provide varying degrees of relief from allergy symptoms. Avoidance

Complete avoidance of allergenic pollen or mold means moving to a place where the offending substance does not grow and where it is not present in the air. But even this extreme solution may offer only temporary relief since a person who is sensitive to a specific pollen or mold may subsequently develop allergies to new allergens after repeated exposure. For example, people allergic to ragweed may leave their ragweed-ridden communities and relocate to areas where ragweed does not grow, only to develop allergies to other weeds or even to grasses or trees in their new surroundings. Because relocating is not a reliable solution, allergy specialists do not encourage this approach.

There are other ways to evade the offending pollen: remaining indoors in the morning, for example, when the outdoor pollen levels are highest. Sunny, windy days can be especially troublesome. If persons with pollen allergy must work outdoors, they can wear face masks designed to filter pollen out of the air and keep it from reaching their nasal passages. As another approach, some people take their vacations at the height of the expected pollinating period and choose a location where such exposure would be minimal. The seashore, for example, may be an effective retreat for many with pollen allergies.

Mold allergens can be difficult to avoid, but some steps can be taken to at least reduce exposure to them. First, the allergy sufferer should avoid those hot spots mentioned earlier where molds tend to be concentrated. The lawn should be mowed and leaves should be raked up, but someone other than the allergic person should do these chores. If such work cannot be delegated, wearing a tightly fitting dust mask can greatly reduce exposure and resulting symptoms. Travel in the country, especially on dry, windy days or while crops are being harvested, should be avoided as should walks through tall vegetation. A summer cabin closed up all winter is probably full of molds and should be aired out and cleaned before a mold-sensitive person stays there.

Around the home, a dehumidifier will help dry out the basement, but the water extracted from the air must be removed frequently to prevent mold growth in the machine.

Those with dust allergy should pay careful attention to dust- proofing their bedroom. The worst things to have in the bedroom are wall-to-wall carpets, venetian blinds, down-filled blankets, feather pillows, heating vents with forced hot air, dogs, cats, and closets full of clothing. Shades are preferred over venetian blinds because they do not trap dust. Curtains can be used if they are washed periodically in hot water to kill the dust mites. Bedding should be encased in a zippered, plastic, airtight, and dust-proof cover.

Although shag carpets are the worst type for the dust-sensitive person, all carpets trap dust and make dust control impossible. In addition, vacuuming can contribute to the amount of dust, unless the vacuum is equipped with a special high-efficiency particulate air (HEPA) filter. Wall-to-wall carpets should be replaced with washable throw rugs over hardwood, tile, or linoleum floors. Reducing the amount of dust in a home may require new cleaning techniques as well as some changes in furnishings to eliminate dust collectors. Water is often the secret to effective dust removal. Washable items should be washed often using water hotter than 130 degrees Fahrenheit. Dusting with a damp cloth or oiled mop should be done frequently.

The best way for a person allergic to pets, especially cats, to avoid allergic reactions is to find another home for the animal. There are, however, some suggestions that help keep cat allergens out of the air: bathe the cat weekly and brush it more frequently, remove carpets and soft furnishings, and use a vacuum cleaner with a high-efficiency filter and a room air cleaner (see section below). Wearing a face mask while house and cat cleaning and keeping the cat out of the bedroom are other methods that allow many people to live more happily with their pets.

Irritants such as chemicals can worsen airborne allergy symptoms and should be avoided as much as possible. For example, during periods of high pollen levels, people with pollen allergy should try to avoid unnecessary exposure to irritants such as dust, insect sprays, tobacco smoke, air pollution, and fresh tar or paint.

Air conditioners and filters

Use of air conditioners inside the home or in a car can help prevent pollen and mold allergens from entering. Various types of air-filtering devices made with fiberglass or electrically charged plates may help reduce allergens produced in the home. These can be added to the heating and cooling systems. In addition, portable devices that can be used in individual rooms are especially helpful in reducing animal allergens.

An allergy specialist can suggest which kind of filter is best for the home of a particular patient. Before buying a filtering device, it is wise to rent one and use it in a closed room (the bedroom, for instance) for a month or two to see whether allergy symptoms diminish. The air-flow should be sufficient to exchange the air in the room five or six times per hour; therefore, the size and efficiency of the filtering device should be determined in part by the size of the room.

Persons with allergies should be wary of exaggerated claims for appliances that cannot really clean the air. Very small air cleaners cannot remove dust and pollen-and no air purifier can prevent viral or bacterial diseases such as influenza, pneumonia, or tuberculosis. Buyers of electrostatic precipitators should compare the machine's ozone output with Federal standards. Ozone can irritate the nose and airways of persons with allergies, especially those with asthma, and can increase the allergy symptoms. Other kinds of air filters such as HEPA filters do not release ozone into the air.

Medication

For people who find they cannot adequately avoid the allergens, the symptoms often can be controlled with medications. Effective medications that can be prescribed by a physician include antihistamines, topical nasal steroids, and cromolyn sodium--any of which can be used alone or in combination. Many effective antihistamines and decongestants also are available without a prescription.

Antihistamines. As the name indicates, an antihistamine counters the effects of histamine, which is released by the mast cells in the body's tissues and contributes to allergy symptoms. For many years, antihistamines have proven useful in relieving sneezing and itching in the nose, throat, and eyes and in reducing nasal swelling and drainage.

Many people who take antihistamines experience some distressing side effects: drowsiness and loss of alertness and coordination. In children, such reactions can be misinterpreted as behavior problems. During the last few years, however, antihistamines that cause fewer of these side effects have become available by prescription. These new nonsedating antihistamines are as effective as other antihistamines in preventing histamine-induced symptoms, but do so without causing sleepiness.

Topical nasal steroids. This medication should not be confused with anabolic steroids that have serious side effects. Topical nasal steroids are anti-inflammatory drugs that stop the allergic reaction. In addition to other beneficial actions, they reduce the number of mast cells in the nose and reduce mucus secretion and nasal swelling. The combination of antihistamines and nasal steroids is a very effective way to treat allergic rhinitis. Cromolyn sodium. Cromolyn sodium stops allergic reactions from starting. It is administered as a nasal spray, and it can prevent the release of chemicals like histamine from the mast cell. Immunotherapy

Immunotherapy, or a series of allergy shots, is the only available treatment that has a chance of reducing the allergy symptoms over the long haul. Patients receive injections of increasing concentrations of the allergen(s) to which they are sensitive. These injections reduce the amount of IgE antibodies in the blood and cause the body to make a protective antibody called IgG. About 85 percent of patients with allergic rhinitis will have a significant reduction in their hay fever symptoms and in their need for medication within 24 months of starting immunotherapy. Many patients are able to stop the injections with good, long-term results. As better allergens for immunotherapy are produced, this technique will become an even more effective treatment.

Allergy Research

The National Institute of Allergy and Infectious Diseases (NIAID) conducts and supports research on allergies focused on understanding what happens to the body during the allergic process-the sequence of events leading to the allergic response and the factors responsible for allergic diseases. This understanding will lead to better methods of preventing and treating allergies.

NIAID supports a network of Asthma, Allergic and Immunologic Diseases Cooperative Research Centers throughout the United States. The centers encourage close coordination among scientists studying the immune system, genes, biochemistry, and pharmacology. This interdisciplinary approach helps move research knowledge as quickly as possible from research scientists to physicians and their allergy patients.

Educating patients and health care workers is an important tool in controlling allergic diseases. All of these research centers conduct and evaluate educational programs focused on methods to control allergic diseases.

NIAID's National Cooperative Inner-City Asthma Study Centers are examining ways to prevent asthma in minority children in inner- city environments. Asthma, a major cause-of illness and death among these children, is provoked by a number of possible factors, including allergies to airborne substances.

Although several factors provoke allergic responses, scientists know that heredity is a major influence on who will develop an allergy. Therefore, researchers are trying to identify and describe the genes that make a person susceptible to allergic diseases.

Other studies are aimed at seeking better ways to diagnose and treat people with allergic diseases and to better understand the factors that regulate IgE production in order to reduce the allergic response in patients. Several research institutions are focusing on ways to influence the cells that participate in the allergic response.

These studies offer the promise of improving treatment and control of allergic diseases and the hope that one day allergic diseases will be preventable as well.

  Information Resources

   American Academy of Allergy and immunology.
   611 East Wells Street
   Milwaukee, WI 53202
   1-800-822-ASMA

   Asthma and Allergy Foundation of America
   1125 15th Street, NW, Suite 502
   Washington, DC 20005
   1-800-7-ASTHMA

   Allergy and Asthma Network
   3554 Chain Bridge Road, Suite 200
   Fairfax, VA 22030
   1-800-878-4403

   For information on air-cleaning devices:

   Environmental Protection Agency
   Public Information Service
   401 M Street, SW
   Washington, DC 20460
   1-800-438-4318