Core Tip: Since there are many types of allergies and the treatment is different, only with allergen testing can we confirm or rule out what we are allergic to, while the determination of allergens is crucial to the treatment of diseases like allergic cough, allergic dermatitis, allergic asthma, etc.
Why is allergen testing necessary?
The onset and development of many skin diseases in clinical practice are associated with exposure to allergens. Most patients with allergic diseases are usually treated for symptom relief without finding the real cause of the allergy, and therefore cannot do targeted prevention and treatment, resulting in repeated aggravation and prolongation of the disease. Therefore, it is recommended that patients with frequent allergies must undergo allergen screening tests to find out whether contact, ingestion or inhalation allergens are causing the allergic reactions in order to solve the problem at the root. Don’t ignore allergies as a minor problem and neglect the examination and treatment, which will eventually lead to serious consequences.
Inhalant allergen screening test: The first step in atopic allergic reaction detection. phadiatop screening reagent contains common allergens in the air such as dust, pollen, fungi, mites, dander, etc. If the patient is allergic to them and has SigE in the serum, the phadiatop test result will be positive. If the test result is positive, the patient’s symptoms are caused by an allergic reaction and further specific allergen testing is required to determine the causative allergen; if the test result is negative, the patient’s symptoms are not caused by common allergens.
Food allergen screening test: This is a screening test for soy, peanut, milk, egg, wheat and fish. If the patient is allergic to one of these, the serum contains SigE and fx5E and the test result is positive. If the test result is positive, it indicates that the patient’s symptoms are caused by an allergic reaction. Specific tests for the above foods should be performed to identify the causative allergen or to avoid the above foods and foods containing the above food components. If the test result is negative, the patient’s symptoms are not caused by the above allergens and the above foods can be consumed safely.
Total serum IgE test: This is a quantitative measurement of the total IgE level in human serum or plasma. High levels of circulating total IgE antibodies are often associated with allergic reactions. If the measured value is less than 60ku/L, it indicates that the patient’s symptoms are probably not caused by an allergic reaction, and allergic disease can be ruled out in combination with the fx5E and Phadiatop tests. If the value is greater than 60ku/L, allergic disease should be highly suspected.
Specific IgE (SigE) test: It is a test for a specific allergen, such as milk, egg, fish, house dust mite, chicken, duck feathers, dog feathers, pear, peach, etc. It is generally divided into 7 levels from 0 to 6. Level 0 is not allergic, level 1 is less allergic, and level 6 is the most severe allergy.
Examination methods for allergen detection.
It can be divided into in vivo test and in vitro test. In vivo test is to apply allergens to the human body through skin testing or prick and other methods to observe the body’s reaction to allergens and determine whether the patient is allergic to these allergens; in vitro test is to take the patient’s blood or other body fluids for in vitro testing, allergens are not directly applied to the human body.
1.In vivo test
(1) Intradermal test.
Through intradermal injection of allergens, after a certain period of time to observe the skin reaction, according to the skin reaction to determine whether the allergy to this allergen.
(2) Prick test.
The prick test can be considered a special intradermal test, which is performed by first placing a drop of the prick skin test solution on the skin and then using a prick needle to pass through the drop and prick it into the skin. The skin puncture solution is only one ten-thousandth of the intradermal test, which is safer. Due to the small skin lesions, patients are painless. Our department uses an internationally standardized antigen, the German Aroger puncture fluid. Inhalant allergens include mites, molds, Artemisia, elm and poplar, animal fur, pollen, etc. Food allergens include fish, shrimp, crab, pork, beef and mutton, milk, eggs, beans, peanuts, spices, etc. All 15 minutes to produce results.
Principle: When a certain allergen enters the skin, patients with tachyphylactic allergic reactions to certain substances immediately and specifically cause degranulation of mast cells in the skin, releasing histamine and other active substances, resulting in local capillary dilation (erythema) and increased capillary permeability (edema, wind mass), and a positive result indicates allergy to the antigen.
Operation method: first put a drop of the puncture skin test solution on the skin, then use a puncture needle to pass through the drop and gently pierce into the skin.
(3) Patch test.
The patch test is mainly used for the examination of contact dermatitis. The specific method is to apply the reagent to the skin and observe it for a period of time, and then determine whether the skin is allergic to the substance according to the skin’s reaction to the contact. The European standardized patch reagent is used for accurate detection. It includes allergens of hundreds of sub-categories in twenty categories, such as drugs, rubber products, skin care products, preservatives, toys, home furnishing materials, hair dyes, printing materials, textile dyes, bleaching agents, metal jewelry, spices and other industrial and agricultural and daily chemical products.
Principle: The suspected allergenic substance is applied to the patient’s skin, and the antigen is presented to the T lymphocytes by the antigen presenting cells after entering the body through the skin or mucous membrane, which activates the specific T lymphocytes and induces the inflammatory reaction.
Indications.
1, contact dermatitis, eczema, occupational dermatoses and other skin diseases that occur as a result of metamorphic reactions caused by exposure to certain substances.
2, when the cause of the disease is unknown or there are several substances contact, need to find the cause of the disease, can do patch test.
Specific method: the reagent is applied to the skin and observed for a period of time, according to the skin’s reaction to the contact to determine whether the substance is allergic.
(4) Cosmetic allergy testing.
The allergens and allergic cosmetics are accurately detected by closed patch method, light patch method, blister blister test method and scratch test method, and patients are guided to choose suitable cosmetics. Our department uses European standardized patch reagents for accurate testing. The photo-patch test is a skin test that detects phototoxic and photoallergic dermatitis photosensitizers and the body’s phototoxic or photoallergic reaction to certain photosensitizers by applying them directly on the skin surface and receiving a certain dose of appropriate wavelength ultraviolet radiation at the same time. Light patch test should be performed to confirm the presence or absence of photosensitive substances when suffering from light allergic skin disease. The method is the same as that of the general patch test, in which the test article is first applied to the patient’s back or forearm flexor side and irradiated with UVB (280-320 nm) and (320-400 nm) at the same time to determine the minimum erythema (MED). 24-48 hours later, half of the patch is irradiated with 3/4 MED light and the results are observed after another 48 hours, if If only redness, swelling or small papules (sometimes small blisters) occur in the patch + irradiated area, the substance is considered.
2.In vitro test
(1) Germany MEDIWISS “Sensitization” quantitative allergen detection system.
Sensitive sieve allergen detection system is a technologically advanced, creative quantitative allergen detection system, which will be used for research purposes of immunoblot technology applied to the laboratory daily diagnosis, using special combinations of allergens for different diseases. The system can be used for the screening of antibodies to a wide range of diseases, with a reliable method and specificity similar to that of skin tests, and is consistent with the results of conventional in vitro single allergen detection tests. Mainly for type I allergic reactions detection IgE, only a drop of serum is needed to easily detect allergens. It is characterized by a high accuracy rate.
(2) Food intolerance testing.
Many chronic diseases have been clinically proven to be food-related, and the symptoms disappear after the problematic food is removed, which is called food intolerance. Food intolerance testing is also the only late-response test for food allergies. Chronic symptoms such as diarrhea, mouth ulcers, hives, acne, migraines, easy fatigue, depression, asthma, sleep disorders, and teeth grinding should be tested for food intolerance if no cause can be identified, all of which may be related to food intolerance.