Immunotherapy - How does immunotherapy work? When is immunotherapy helpful?

Jan 10 2008

Those who suffer from allergic asthma, rhinitis, conjunctivitis or stinging insect allergies may be good candidates to receive immunotherapy, also known as "allergy shots," according to the American Academy of Allergy, Asthma & Immunology (AAAAI).

"Immunotherapy is a form of treatment that aims to decrease sensitivity to substances called allergens," said Linda Cox, MD, FAAAAI, Chair of the AAAAI's Immunotherapy and Allergy Diagnostics Committee. "Allergens, like pollen, mold or animal dander, are substances that trigger allergy symptoms when an allergic person is exposed to them. Patients who receive immunotherapy are injected with increasing amounts of an allergen until the target therapeutic dose is reached, in an effort to build resistance to specific allergens."

Immunotherapy has proven to prevent the development of new allergies, and it may prevent the progression of allergic disease from allergic rhinitis to asthma. Immunotherapy can also lead to long-lasting relief of allergy symptoms after treatment is stopped.

How does immunotherapy work?

Immunotherapy works like a vaccine. Your body responds to the injected amounts of a particular allergen, given in gradually increasing doses, by developing immunity or tolerance to the allergen(s). As a result, allergy symptoms decrease or minimize when you are exposed to that allergy in the future.

There are generally two phases to immunotherapy: -- Build-up phase: This involves receiving injections with increasing amounts of the allergens about one to two times per week. The length of this phase depends upon how often the injections are received, but generally ranges from three to six months on a conventional build-up schedule. The target dose may be reached in a much shorter period of time (one day to several weeks) with rapid build-up schedules, referred to as "cluster and rush." These rapid schedules involve giving two or more injections each visit, which will decrease the number of visits during the build-up phase. However, these schedules may also carry a greater risk of patients experiencing an adverse reaction to the immunotherapy. -- Maintenance phase: This begins once the effective therapeutic dose is reached. The effective maintenance dose depends on the patient's level of allergen sensitivity and his or her response to the immunotherapy build-up phase. During the maintenance phase, there will be longer periods of time between immunotherapy treatments, ranging from two to four weeks. Your allergist/immunologist will determine what range is best for you.

You may notice a decrease in symptoms during the build-up phase, but it could take as long as 12 months on the maintenance dose to notice an improvement. The effectiveness of immunotherapy treatments appears to be related to how long the treatment lasts, as well as the dose of the allergen. If you haven't seen recognizable improvement after a year of maintenance therapy, work with your allergist/immunologist to discuss other treatment options.

When is immunotherapy helpful?

Immunotherapy is recommended for those with allergic asthma, rhinitis, conjunctivitis and stinging insect allergies. Immunotherapy for food allergies is not recommended. The best option for people with food allergies is strictly to avoid that food.

Immunotherapy should only be prescribed by physicians with specialty training in allergy/immunology and should be administered in a facility equipped with proper staff and equipment to identify and treat adverse reactions to allergy injections. Ideally, immunotherapy should be given in the prescribing allergist/immunologist's office, but if this is not possible, your allergist/immunologist should provide the supervising physician with comprehensive instructions about your immunotherapy treatment.

When to see an allergist/immunologist

According to the AAAAI's referral guidelines, patients should see an allergist/immunologist if they:

• Have a clear relationship between asthma, rhinitis, conjunctivitis and exposure to an allergen
• Have a poor response to medications or avoidance measures
• Have a long duration of allergy symptoms (a majority of the year)
• Are a child with rhinitis, because of the potential preventive role of allergen immunotherapy in the progression of allergic disease.

The AAAAI represents allergists, asthma specialists, clinical immunologists, allied health professionals and others with a special interest in the research and treatment of allergic disease. Allergy/immunology specialists are pediatric or internal medicine physicians who have elected an additional two years of training to become specialized in the treatment of asthma, allergy and immunologic disease. Established in 1943, the AAAAI has more than 6,500 members in the United States, Canada and 60 other countries.