June 16, 2022 – What would you do if you thought you had serious health problems, but the best way to know for sure could kill you?

This is a reality for patients who want to confirm or rule out a food allergy. Cindy Tang, PhDAssociate Professor of Mechanical Engineering at Stanford University in California.

It is for this reason that Tang and her colleagues are developing a food allergy test that is not only safer, but more reliable than today’s tests. AT paper In the magazine Lab on a chipTang and colleagues are outlining the basis for this future test, which isolates a food allergy marker from the blood using a magnetic field.

How Today’s Food Allergy Tests Fail

The gold standard for diagnosing food allergies is what is called an oral food problem. This is when the patient eats gradually increasing amounts of problem foods, say peanuts, each day. 15 to 30 minutes to see if symptoms occur. This means that patients with severe allergies may be at risk of anaphylaxis, an allergic reaction that causes inflammation so severe that breathing becomes restricted and blood pressure drops. Because of this, the clinical team must be on the alert with treatments such as oxygen, epinephrine, or albuterol.

“The test is very accurate, but potentially unsafe and in rare cases even fatal,” Tan says. “This has led to a lot of bogus tests appearing on the internet claiming hair samples are being used for food tests, but they are inaccurate and potentially dangerous as they could give someone a false sense of certainty that they should avoid foods. “.

Less risky tests are available, such as skin prick tests – these include applying a small amount of food to the patient’s arm, as well as blood tests that measure allergen-specific antibodies.

“Unfortunately, both are not as accurate and have a high false positive rate,” Tan says. “The best method is a food challenge, which many patients are afraid to do, which is not surprising.”

The future of food allergy testing: faster, safer, more reliable

In their study, the Stanford researchers focused on a type of white blood cell known as basophils, which release histamine when exposed to allergens. With the help of magnetic nanoparticles that bind to certain blood cells, but No basophils, they were able to separate basophils from blood using a magnetic field in just 10 minutes.

Once isolated, the basophils are exposed to potential allergens. If they react, it’s a sign of an allergy.

Basophils have been isolated in the lab before, but not as quickly or efficiently, Tang says.

“For true basophil activation, you need fresh blood, which is tricky when you have to send it to the lab,” Tan says. “Being able to perform such tests in a clinic or in our own laboratory would be a big step forward.”

Next steps

While this represents a breakthrough in basophil activation testing, more research is needed to fully develop the system for clinical use. The researchers say it should be standardized, automated and miniaturized.

However, the results give hope to those with food allergies that tomorrow’s gold standard test will only require a blood sample without an ambulance crew on duty.

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