New test developed to simplify allergy diagnosis

Researchers at the University of Bern and the University Hospital of Bern have developed a test to simplify the diagnosis of allergies. Its effectiveness has now been confirmed in clinical samples from children and adolescents suffering from peanut allergy. The results could fundamentally improve the clinical diagnosis of allergies in the future.

Food allergies are a major health problem worldwide. In some countries, up to 10% of the population is affected, mostly young children. Peanut allergy, in particular, is one of the most common illnesses and often presents with severe, potentially life-threatening reactions. The stress of food allergies not only affects the individuals concerned, but also has far-reaching consequences for their families, the health system and the food industry. The oral food challenge test, in which people consume the allergen (such as peanut extract) under supervision to test the allergic reaction, is still considered the gold standard in diagnosis. However, the method is complex and carries health risks. Allergen skin testing and blood testing are often not very accurate, which can lead to misdiagnoses and unnecessary food avoidance.

A team of researchers led by Professor Dr. Alexander Eggel from the Department of Biomedical Research (DBMR) at the University of Bern and the Department of Rheumatology and Immunology at the University Hospital of Bern and Prof. Dr. Thomas Kaufmann from the Institute of Pharmacology at the University of Bern developed an alternative test in 2022. It mimics the allergic reaction in a test tube and thus offers an attractive alternative to standard tests. Researchers from Bern have now investigated the effectiveness of the test in samples from children and adolescents with confirmed peanut allergy and a healthy control group in a clinical study in collaboration with colleagues from the Hospital for Sick Kids in Toronto, Canada. They were able to show that the new test has a higher diagnostic accuracy than the methods used until now. The study was recently published in the European Journal for Allergy and Clinical Immunology (Allergy).

Mast cell activation test as a suitable alternative

“The most common food allergies are type I allergies. They develop when the body produces immunoglobulin E (IgE) antibodies in response to substances that are actually harmless (allergens),” explains Alexander Eggel. These antibodies bind to specific receptors on mast cells, which are immune system cells that play an important role in allergic reactions and inflammation. They are mainly located in tissue, for example, in the intestinal mucosa, and are primed and sensitized to the allergen by binding to antibodies. Upon renewed contact with the allergen, it binds directly to the antibody-laden mast cells, activating them and triggering an allergic reaction.

In the Hoxb8 Mast Cell Activation Test (Hoxb8 MAT), which we developed, mast cells grown in the laboratory are contacted with blood serum from allergic patients. Mast cells bind IgE antibodies from serum and are sensitized by them. We can then stimulate the mast cells with different amounts of allergens to test.”

Prof. Dr. Alexander Eggel, Department of Biomedical Research (DBMR), University of Bern

Quantification of activated mast cells indicates how allergic a patient is to the tested allergen without having to consume the food.

Higher diagnostic accuracy than standard tests

The study used serum samples from a total of 112 children and adolescents who had already participated in a study in Canada and for whom clear diagnostic data on peanut allergy status were available. Mast cells cultured in the laboratory were sensitized with their own serum and then stimulated with peanut extract. “The cell-based test was easy to perform and worked perfectly. All samples were measured within two days, which was very fast,” says Thomas Kaufmann. The results showed that a large number of sera from allergic patients showed allergen-dependent activation, whereas almost all samples from non-allergic control subjects did not activate mast cells. “An extremely high diagnostic accuracy of 95% could be calculated from this data,” adds Eggel.

In addition, the data measured in the study were analyzed in direct comparison with other diagnostic methods established in the hospital. The Hoxb8 MAT test was found to have significantly higher accuracy than the standard measurement of allergen-specific IgE antibodies in the blood or the commonly used skin test. “Comparison with other clinical tests was crucial to determine which one best reflects the allergic response of patients. The new mast cell activation test has the advantage of being functional and thus incorporates many parameters that are important for allergy activation,” says Thomas Kaufmann, adding: “The new test is also based on stable blood serum, which can be obtained with a simple blood draw and then stored in a freezer. This eliminates the demanding logistical hurdles that arise with other methods.” The study also showed that the Hoxb8 MAT test leads to fewer false negatives.

“What has been demonstrated in this study regarding the diagnosis of peanut allergies can also be applied to other allergies in a simple way. The technology is a perfect example of how basic research from the University of Bern can be translated into clinical practice and could ultimately simplify life for patients and doctors,” concludes Eggel.