King's College London

Researchers from the School of Immunology & Microbial Sciences and the Medical Research Council (MRC) have developed a new test to diagnose peanut allergy.

Currently used methods include a skin-prick test which can result in over-diagnosis or a feeding test which can be time-consuming and sometimes lead to severe allergic reactions. The new proposed test called the mast activation test (MAT) doesn’t run the risk of false-positives or causing anaphylactic shock.

The MAT is five times more cost-efficient compared to the feeding test and could be adapted to test for other food allergies.

Dr Alexandra Santos, an MRC Clinician Scientist from the Peter Gorer Department of Immunobiology and lead author, said: “The current tests are not ideal. If we relied on them alone, we’d be over diagnosing food allergies – only 22% of school-aged children in the UK with a positive test to peanuts are actually allergic when they’re fed the food in a monitored setting.”

Peanut allergy symptoms occur when peanut proteins interact with an antibody called immunoglobulin E (IgE) which sets off the allergic reactions such as skin reactions, itching or constricting of the mouth, throat and airways, and digestive problems. The new test works by focussing on mast cells, which are activated when immunoglobulin E is present, and send out a specific kind of biomarker which can be detected in the blood test. 

Dr Santos added: “We are adapting this test to other foods, such as milk, eggs, sesame and tree nuts. This test will be useful as we are seeing more and more children who have never been exposed to these foods because they have severe eczema or have siblings with allergies.

The study was published in the Journal of Allergy and Clinical Immunology here.