A New Test Diagnoses Peanut Allergies with High Specificity
One major challenge in peanut allergy diagnosis is that the tests commonly used to determine if the allergy exists frequently produce false positives. False positives are preferable to false negatives, which would lead to the incorrect assumption that those with peanut allergies do not have the allergy and thereby increase their likelihood of ingesting peanuts and thus their risk for allergic reactions.
However, the existence of false positives makes it difficult to know for certain if some people who tests positive for food allergies based on a skin test or an antibody test are truly allergic to peanuts. The result is that many of these people are then put through food challenges, where they are given increasingly larger doses of peanut proteins until they either have an allergic reaction or are deemed not to be allergic. Going through a food challenge can be unpleasant, especially for those who are allergic to peanuts and therefore experience an allergic reaction during the process.
A new test, called the mast cell activation test, or MAT, can now diagnose peanut allergies with a much higher degree of specificity than the conventionally used skin tests and antibody tests. A study showing that this degree of specificity is approximately 98% was recently published in the Journal of Allergy and Clinical Immunology.
As part of their investigation into a peanut allergy test with high specificity, the researchers studied 174 children, 73 of whom had peanut allergy, 60 of whom were sensitized to peanuts but not allergic, and 41 of whom were neither sensitized nor allergic. They looked not only at the activation of their mast cells, which is certain cells of the immune system known to be involved in allergic reactions but also at the activation of a similar type of cell, called basophils.
Given that testing mast cell activation provided a higher degree of specificity for diagnosing peanut allergy than did testing basophil activation, the researchers concluded that MATs are the more promising test for helping to diagnose peanut allergies in the context of current methods for diagnosis and their specific limitations. Future work will focus on adapting MAT to other types of food allergies, such as those to milk, eggs, and other seeds and nuts. The hope is that eventually, far fewer patients will have to undergo food challenges to determine whether they have food allergies.