This simple test could reveal if you have a peanut allergy and tell you just how severe your allergy is

I don’t remember my first allergic reaction but I’ve heard the story enough times to recall it. After stealing a Snickers from my sister as a child, my throat swelled up, my cheeks blew up to the size of a balloon, and I’ve tried to avoid peanuts ever since.

Allergies, like mine, can be fatal and thanks to the use of blood and skin-prick tests, are being diagnosed much earlier than before. Unfortunately, such tests are prone to false positives and over-simplification. This makes it difficult for people to know whether they have a sensitivity to certain foods or if they have an actual food allergy. 

Oral food challenges (OFCs) are often the second line of defence if one of the above tests are inconclusive, but they’re as risky as they sound. The test works by feeding people increasingly higher quantities of peanuts, or other food-based allergens to confirm the allergy outright. 

 Now, researchers at the MRC & Asthma UK Centre in Allergic Mechanisms of Asthma have developed a new food allergy test that is not only claimed to be 98% accurate, it doesn’t come with any of the risks associated with the OFC.

Called the mast activation test (MAT), this test looks at the patient’s mast cells, known to play a part in triggering an allergic reaction. It’s known that mast cells are activated when allergens interact with the antibody immunoglobulin E (IgE), and this is what causes the allergic reaction to occur. The activation of mast cells can be triggered in the lab with just the use of a blood sample.

“The mast cell activation test is more specific than tests that are usually done in-clinic like the skin-prick test or IgE test to detect allergy antibodies called IgE antibodies. Being more specific means that when it is positive, it means allergy, as opposed to current tests which have a lot of false-positives,” Dr. Alexandra Santos, MRC clinician scientist and lead author of the study, tells me. “The mast cell activation test is also safer and less expensive than the oral food challenge.”

In the team’s study, published in the Journal of Allergy and Clinical Immunology, the researchers took blood samples from 174 children (73 allergic to peanuts and 101 peanut-tolerant) and added the peanut protein to their mast cells. Incredibly, MAT was able to accurately identify people with a nut allergy with 98% specificity. 

What’s more, the test also reflected the severity of the patients’ nut allergy by looking at the number of mast cells activated.

“The mast cell activation test can be developed to any allergen,” Santos added. “We are adapting this test to other foods such as milk, eggs, sesame and tree nuts.”

When exactly we could see the MAT test be put in place in clinics is currently unclear, but in its current form, it’s ready.

“It is hard to say exactly when it will be in routine use,” Santos told Alphr. “Scientifically and clinically, it is ready to be used to test for peanut allergy in the UK. To make it routinely available, we need to roll it out to diagnostic labs and this can take a few years.”

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