A recent report published by the Food Standards Agency in the UK [Patterns and prevalence of adult food allergy (PAFA); https://shorturl.at/jnaLY] estimates that around 6% of the UK adult population have a clinically confirmed IgE-mediated food allergy.

Other data estimate that the number of people in the UK with IgE-mediated food allergy has doubled in the last decade and that around 10 people each year die in England and Wales as a result of food allergy. The challenges of living with a severe food allergy are serious. Food companies are being urged to do more with regards to labelling and the hospitality industry has to put effort into properly training its staff. People with allergies also have to be cautious on public transport – many of us have probably experienced air travel where a nut ban has been announced because of a passenger with a serious allergy. New research suggests that there is no evidence to support airborne transmission of nut allergens but that the most effective action is for passengers with allergies to wipe down their seat area (including tray table and seatback entertainment system) before settling in for the journey [1]. Given the changes to lifestyle that have to be accommodated by people with food allergies it is important that diagnosis is accurate. However, diagnosis of a food allergy is not necessarily straightforward. The patient’s history forms a good start, but the oral food challenge remains the gold standard diagnostic process, although this is resource-intensive and time-consuming and risks provoking a systemic allergic reaction. Generally, a diagnosis is reached through a variety of stages: a skin-prick test (SPT), followed by serological quantification of allergen-specific IgE (sIgE). However, these tests have high sensitivity but fairly low specificity, and so could result in overdiagnosis. The baso-phil activation test (BAT) is a functional cell-based assay with assesses the activation of basophils – which are effectors of the allergic reaction. This test works well to in the diagnosis of nut allergies and also is better than other tests at differentiating between allergy or intolerance. However, limitations including non-response from some donors and the need to process fresh blood samples within 24 hours have hampered wider use of the BAT. A recent study has shown that a new mast cell activation test (MAT) technology has the ability to overcome the limitations of the BAT [2]. This test uses mouse mast cell progenitors that stably express the human high-affinity IgE receptor, FcεRIα, and that are conditionally immortalized with the homeobox B8 gene (Hoxb8 MCs), the so-called Hoxb8 MAT. The test uses patient serum to sensitize the in vitro cultured Hoxb8 MCs, so there is no need for fresh blood samples. Results from the Hoxb8 MAT study showed that diagnostic accuracy was highest at allergen concentrations ≥100 ng/mL, with an area under the receiver operating characteristic curve of 0.97, 93% sensitivity, and 96% specificity. Additionally, the test was able to accurately classify BAT non-responders into allergic versus non-allergic patients. Although the BAT requires approximately 100 times lower allergen concentrations to induce a comparable percentage of cell activation, the authors argue that:

The absolute concentration of allergen needed to activate the cells is secondary to the optimal discrimination of activated versus nonactivated cells at a given allergen concentration in samples from allergic and nonallergic individuals.

The Hoxb8 MAT looks like a great way forward for accurate peanut allergy diagnosis and it will be interesting to see what other allergies may be assessed with similar technology in the future.

Peanut allergy needs accurate diagnosis to prevent unnecessary lifestyle modifications (Adobe Stock.com)

Read the research

1. Turner P, Dowdall N. Flying with nut and other food allergies: unravelling fact from fiction. Arch Dis Child 2024: archdischild-2024-327848 (https://shorturl.at/brDWm).
2. Bachmeier-Zbären N, Celik A, van Brummelen R et al. Clinical utility analysis of the Hoxb8 mast cell activation test for the diagnosis of peanut allergy. Allergy 2024 (https://shorturl.at/OsXJb).