Food allergies are a major health problem worldwide. In some countries, up to 10% of the population is affected, mainly young children. Peanut allergy, in particular, is one of the most common diseases and often manifests itself in severe reactions that can be life-threatening. The stress of food allergies not only affects the affected individuals, but also has far-reaching consequences for their families, the healthcare 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 Prof. 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 In 2022, the University of Bern developed an alternative test. It mimics the allergic reaction in a test tube and therefore offers an attractive alternative to standard tests. Researchers from Bern have investigated the effectiveness of the test in samples of children and adolescents with confirmed peanut allergy and a healthy control group in a clinical study in collaboration with partners at the Hospital for Sick Kids in Toronto, Canada. They were able to demonstrate that the new test has greater diagnostic accuracy than the methods used until now. The study was recently published in the European Journal of Allergy and Clinical Immunology (Allergy).
Mast cell activation test as an appropriate alternative
“The most common food allergies are type I. 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 cells that play an important role in allergic reactions and inflammation. They are mainly found in tissue, for example in the intestinal mucosa, and are primed and sensitized to the allergen by binding to antibodies. After new contact with the allergen, it binds directly to mast cells loaded with antibodies, activating them and causing an allergic reaction. “In the Hoxb8 mast cell activation test (Hoxb8 MAT) that we have developed, mast cells cultured in the laboratory are brought into contact with the blood serum of allergic patients. The mast cells bind to IgE antibodies in the serum and are sensitized by them “We can then stimulate the mast cells with different amounts of the allergens to be analyzed,” says Eggel. The quantification of activated mast cells suggests how allergic a patient is to the allergen analyzed without having to consume the food.
Greater 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 their peanut allergy status was available. Mast cells cultured in the laboratory were sensitized with their serum and then stimulated with peanut extract. “The cell 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 exhibited dose-dependent activation of the allergen, while almost all samples from non-allergic control subjects did not activate mast cells. “From these data an exceptionally high diagnostic accuracy of 95% can be calculated,” adds Eggel.
Furthermore, the data measured in the study were analyzed in direct comparison with other established diagnostic methods 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. “The comparison with other clinical tests was crucial to determine which of them best reflected the patients’ allergic reaction. The new mast cell activation test has the advantage that it is functional and therefore incorporates many parameters that are important for trigger the allergy,” says Thomas Kaufmann and adds: “The new test is also based on stable blood serum, which can be extracted by a simple blood sample and then stored in the freezer. This eliminates the difficult logistical obstacles that arise with other methods. “. The study also showed that the Hoxb8 MAT test produces fewer false negative results.
“What has been shown in this study on the diagnosis of peanut allergy can also be easily applied to other allergies. The technology is a perfect example of how basic research from the University of Bern can be put into practice and ultimately simplify the lives of patients and doctors,” concludes Eggel.