Researchers from the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland have created a fast and precise method to test which specific proteins in milk cause allergic reactions in patients. This novel approach not only has the potential to allow the individual to tailor his or her diet and lifestyle to accommodate their specific allergies, but also might one day be broadly utilized to test for a multitude of other food allergies as well.
In the Western world an estimated three percent of adults possess some type of food allergy. This number is even greater among Western children, who have an estimated allergy prevalence of six to eight percent. What is more, experts believe that food allergies are becoming increasingly common in developed nations. The Center for Disease Control and Prevention reports that children and adolescents surveyed in 2009-2011 had a prevalence of food allergies roughly 50 percent greater than their counter-parts who had been surveyed in the previous decade.
When a person finds that they have a food allergy, this reaction is often generalized as being caused by the food source of whatever prompted the allergic reaction. For example, one might describe someone as being allergic to peanuts, eggs, milk, or seafood. While this may help a person avoid foods that will trigger their condition, it is important to recognize that this is an over-simplification. There is no such thing as a single “peanut” molecule or any other equivalent. Rather, the foods that we eat (with the exclusion of the most basic ingredients such as sugars and salt) are comprised of a rich diversity of carbohydrates, fats, and amino acids that combine in distinct ways to form familiar dishes. As such, a single type of food may contain multiple proteins that can cause an allergic reaction. For example, peanuts contain vicilin, albumin, and legumin proteins that can all act as major peanut allergens.
Depending on what specific allergenic protein prompts the immune response, a person may be able to consume some foods but not others. For example, people allergic to the egg allergen ovotransferrin may be able to consume foods that contain baked eggs such as cookies or cakes. This is because the high temperatures utilized to cook the food adequately denature the ovotransferrin protein, rendering it unable to elicit an autoimmune response. However patients allergic to ovomucoid, another allergenic egg protein, cannot consume these baked treats because the cooking process does not destroy the protein’s allergenic functionality.
Knowing the specifics of one’s allergic condition can potentially help improve one’s lifestyle, but identifying a person’s precise allergic profile is often difficult. While a number of different tests such as sub-lingual immunotherapy (SLIT) or sub-cutaneous immunotherapy (SCIT) have been used to test for allergies to specific proteins, many of these tests ignore less common allergies. In addition problems guaranteeing the likeness of the allergens used in the test to their naturally occurring counter-parts continue to be a major challenge in the field of allergology.
To test for what specific proteins in milk triggered an allergic episode, the research team at the EPFL developed a highly sensitive test that examined a patient’ s levels of IgE antibodies during an allergic response. IgE is a particular type of antibody that binds to allergenic proteins and signals other cells to launch an autoimmune response. The researchers first isolated these IgE antibodies from a sample of the patient’s blood. They tagged the IgE with magnetic beads and loaded into an extremely thin tube that measured only about 50 micrometers in diameter. The tube was then flushed out with milk. If the IgE antibodies encountered a recognizable allergenic protein in the milk, they bound to that protein. All other milk proteins exited out the other end of the tube. Chemical rinses then remove the allergenic proteins from the IgE, and mass spectrometry used measurements of molecular weight and electrical charge to specifically identify what exactly in milk triggered the patient’s autoimmune response.
Compared to more conventional methods of allergy testing, this new method is much faster and gives a more detailed picture of a patient’s specific allergic condition. The test also does not create biases against less common allergenic proteins. Perhaps most exciting of all is the broad basis for applications that this test offers. In the future applying such a technique to the precise diagnosis of other allergies such as those from wheat, peanuts, eggs, and fish should be reasonably easy to accomplish.
By Sarah Takushi