Allergy Testing Made Easy

Written by Panamdeep Thind and Edited by Josephine Chan

Current methods for allergen testing consist of needle blood tests and skin prick tests, both of which are often deemed as uncomfortable to the general public, especially for children. As a result, scientists in the medical community have developed a new method: nasal smear. This method has the ability to test 112 allergens through one blood sample [1].

Three common methods to detect for allergies include patch tests, skin prick tests, and blood tests, ranging from being non-invasive to extremely invasive. The patch test is used to determine skin contact allergies, such as contact dermatitis (various skin rashes based on different allergens). In this method, a whole patch containing the specific allergen is placed on the skin to test the specific allergy. If the skin in contact with the patch reacts, the individual is diagnosed with the specific allergy. The next method is one of the most common to detect allergies: the skin prick test. This process includes testing an area on the skin, usually the back of the forearm, using the allergen suspected. If results are inconclusive, an intradermal test is needed, in which the allergen is injected to note for any possible reactions. This particular method is utilized more often than the others because it is fairly accessible and inexpensive to conduct [2].

The least invasive is a serum Immunoglobulin E (IgE)-specific antibody test, more commonly known as an allergen blood test. This blood test is conducted in the same manner as other blood tests, but it measures the level of IgE antibodies, a type of immunoglobulin released through allergic reactions. The allergen blood test relies on the presence of the IgE antibodies as indicators for specific allergies [3]. Many medical tests, including these allergen tests, are difficult to administer, and the process of testing involves prolonged exposure to many variables that may cause an allergic reaction. For instance, the patch test works by exposure to suspected allergies and is only effective if it causes an allergic reaction. Allergen testing has many specifics, where each different type of allergy is detected with a different method. One way to make testing more efficient is to have a single method to test for allergies.

One method that has been developed to diagnose allergic rhinitis (AR), or hay fever, is the nasal eosinophil (nasal smear) method. Hay fever is an extremely common allergic response among the general public that is associated with having a stuffy nose [4]. Allergy tests are quite recurrent within children; therefore, a more gentle method such as nasal smearing is usually preferred. The process delivers the same results as a blood test would, except it uses nasal secretion instead of blood samples. The nasal secretion is obtained by simply blowing into a tissue [4]. In recent clinical trials, the nasal smear method has only been targeted to diagnose AR. However, based on studies, nasal secretion can also be used to measure IgE levels as blood tests can, except in a completely noninvasive manner. Through extensive testing, the IgE levels were determined using nasal fluid and compared to serum IgE levels. A positive response from comparisons to serum IgE shows that the nasal fluid method can be proven to be just as effective [1].

According to all current studies, the nasal smear method has not risen to the same popularity as the other common methods of allergen testing, but it has been proven to be a successful and proper way to test for a variety of allergies. Considering its nature as a  noninvasive way to test for common allergies, its prominence may become increasingly apparent in the future as a gentler method for detecting a larger group of allergies.

References

1. Gökkaya, M., Schwierzeck, V., Thölken, K., Knoch, S., Gerstlauerm M., Gannekm G., Traidl-Hoffmann, C., Gilles, St. (2020) “Nasal Specific IgE Correlates to Serum Specific IgE: First Steps towards Nasal Molecular Allergy Diagnostic.” Allergy.
2. Chang, K., Guarderas, J.. (2018) “Allergy Testing: Common Questions and Answers.” American Family Physician, 98:34-39.
3. Cox, L. (1970)“Overview of Serological-Specific IgE Antibody Testing in Children.” Current Allergy and Asthma Reports, Current Science Inc. 11:447.
4. Johnson, D., Paul, J. (2019) “Exploring the Anti-Allergic Property of Potentized Sodium Chloride Using Nasal Eosinophil Count as a Criterion.” Muller Journal of Medical Sciences and Research, 10:47.