Allergen immunotherapy is the administration of specific allergens repeatedly to patients that are proven to have IgE-mediated allergies to protect against inflammatory reactions and allergic symptoms associated with the exposure to those allergens. It is a practice that has been going on for nearly a 100 years and has proved to alter naturally the course of allergic disorders like allergic asthma, allergic rhinitis, allergic conjunctivitis and hypersensitivity to insect venom like bee and wasp venom. Recently, this practice has been extended to treat allergies associated with food as well as atopic dermatitis.
When to go for Allergen Immunotherapy
Allergies not only affect the normal way of life to those affected but also cause life-threatening conditions. Taking allergy tests, whether skin tests or blood tests, help to identify specific allergens that are responsible for the allergic symptoms. This aids in the administration of drugs and better still help in avoiding those allergens. Sometimes, these allergic symptoms persist despite the use of medication or the allergens simply become unavoidable, and when this happens, there is another way out allergen immunotherapy. Allergen immunotherapy is recommended in situations where:
- Medication doesn’t work
- Medication has severe side effects
- Allergy symptoms are so severe
- Allergens are difficult to avoid
- By people who want to avoid medication
RAST test
To understand the RAST-based immunotherapy, it is important first to look at the methods of testing allergies. Allergies are commonly identified using the skin test and blood (RAST) test method. Since the interest here is RAST-based immunotherapy, a quick look at the blood test method is important. In an allergic reaction, specific antibodies (IgE) are produced by specific allergens and to determine the presence of these allergens, serum from the patient has to be mixed with different allergens. The blood sample from the patient is added to allergens that are chemically bound to an insoluble matrix. In a positive reaction, the IgE will bind to the allergen after which a labeled anti-IgE is added that attaches to the bound IgE after which identification and quantification are done. This method not only identifies allergens but also shows the levels of hypersensitivity to specific allergens.
RAST-based allergen immunotherapy
Allergen immunotherapy involves a controlled exposure to already known allergens to reduce the severity of allergic symptoms or disorders. The process is usually long, and it can take up to six months to realize initial progress and up to 5- 6 years to see the full benefits. The process is about slowly allowing the immune system to tolerate allergens. At first, a small dose of the allergen is introduced and then it is increased overtime. When going for immunotherapy, it is necessary first to identify initial treatment doses that are considered safe, and this is where RAST scoring system becomes a reliable method to identify those dose levels.
RAST testing for allergens can quantify the levels of specific IgE that are produced in response to a specific allergen and allows for the selection of safe immunotherapy doses for each allergen. For instance, when the degree of hypersensitivity is low or moderate, the starting allergen concentrations to be administered is higher leading to reduced time and number of doses to be administered entirely. When the level of sensitivity is high, the starting concentration of allergen doses needs to be low due to the high caution that has to be taken.
Depending on the level of sensitivity to different allergens, the initial concentration dose to be given to each patient should be inversely proportional to the respective degree of sensitivity.
Understanding Allergy Diagnoses
Allergies are a very common problem. One in five Americans have symptoms of allergies or asthma, and over half of people tested for allergies test positive for one or more allergies. Despite the commonness of allergies, it can be difficult to understand your allergy diagnosis.
Medical History and Symptoms
Your allergy diagnosis will begin with your doctor taking a medical history and asking you about your symptoms. They will also perform a physical exam to check for any common allergy symptoms.
Allergic Rhinitis
If your allergy symptoms involve a runny or stuffy nose and itchy eyes, you are most likely suffering from allergic rhinitis. These can include pets, pollen, dust, and mold. Your doctor may choose to treat you with medication and forego further testing. Your doctor may be able to tell you what you are most likely to be allergic to based on your symptoms and when they occur.
Drug and Insect Allergies
Drug allergies and allergies to insect stings can cause itching, swelling, hives, and anaphylaxis. Anaphylaxis is a life-threatening condition that can cause nausea, a severe drop in blood pressure, severe breathing difficulty, unconsciousness, and death. These allergies are easily identified because you will develop symptoms after being exposed to your allergen. If you are diagnosed with one of these allergens, you will need to take great care to avoid them.
Allergy Testing
Allergy testing is needed when a medical history and exam isn’t enough to make a diagnosis. They can be performed to diagnose any type of allergy.
Skin Prick Test
A skin prick test is an accurate way to diagnose most allergies, including those caused by environmental allergens, food, and contact allergies. The doctor will place a small amount of the allergen on your skin and prick or scratch it. If you are allergic to the substance, you will develop swelling, redness, and itching at the site within fifteen minutes. A positive test result means that you are likely allergic to the substance.
Blood Tests
Blood tests can be useful when you are taking medications to manage your allergy symptoms or you have very sensitive skin. The doctor will draw your blood. Then the lab will expose your blood to your suspected allergens. They then measure the amount of antibodies your body produces in response to the allergen.
Patch Test
The patch test is generally used when your doctor suspects that you have contact dermatitis. The doctor will place the allergen on your skin and apply a bandage. After 24-48 hours, the doctor will remove the bandage and check for any reaction. Redness and itching at the site means that you are allergic to the substance. The patch test can also be used with trays. The tray has small compartments that contain different allergens. This is an effective way to test for multiple skin allergies at once.