Basophil Activation Test Outperforms SPT and IgE in Milk Allergy Challenge

A recent study identified the basophil activation test as the most accurate test in predicting allergic reactions to baked and fresh cow’s milk during oral food challenges, compared with skin prick testing and IgE testing.1

“Even if sometimes the difference in diagnostic accuracy of [basophil activation tests] and other tests was relatively small, we consider that every additional patient diagnosed correctly is clinically relevant,” wrote study investigator Irene Bartha, PhD, from department of women and children's health (Pediatric Allergy) at King's College London, and colleagues.

Cow’s milk allergy has an estimated worldwide prevalence of 5.7%.2 Research has shown that tolerating baked milk is associated with improved cow’s milk allergy outcomes and quality of life, but current tests—skin prick tests and specific IgE (sIgE)—cannot accurately identify children who can tolerate baked milk without doing an oral food challenge.1 In this study, investigators compared the diagnostic performance of the basophil activation test, the skin prick test, and the specific IgE during fresh milk oral food challenges.

The team recruited children aged 6 months to 15 years who visited various specialized pediatric allergy clinics in London. Children were eligible if they either had a history of an immediate-type allergic reaction to cow’s milk, no history of cow’s milk consumption, or evidence of IgE sensitization as documented by SPT or serum sIgE. Investigators excluded children with significant chronic illness outside of atopic disease, history of severe life-threatening food reactions, inability to undergo a diagnostic food challenge, recent or ongoing systemic immunosuppressive treatments, current use of omalizumab or food allergen immunotherapy, and inability to discontinue antihistamines before skin prick testing.1

Skin prick testing involved cow’s milk extract, fresh milk, and baked milk slurry (prepared the day of the challenge with 1 g of the challenge food in 10 mL of saline), and a single-headed metal lancet. Investigators used 10 mg/mL histamine dihydrochloride and 50% glycerol in buffered saline as positive and negative controls, respectively.1

IgE testing measured total IgE or sIgE levels to cow’s milk, boiled milk, alpha-lactalbumin, beta-lactoglobulin, and casein.1

Lastly, basophil activation testing, conducted by the Santos Lab at King’s College London, used whole blood incubated with milk extract, baked milk, anti-IgE, formyl-methionyl-leucyl-phenylalanine, or controls, followed by staining, flow cytometry, and analysis of basophil activation (%CD63+ and SI CD203c), with non-responders defined as <5% CD63+ basophils to anti-IgE and allergen.1

All children aged ≥ 12 months had a double-blind, placebo-controlled food challenge, and those under 12 years had an open incremental oral food challenge. Among 150 children given a baked milk challenge, 85% tolerated it and proceeded to a fresh milk challenge, of which 56% passed.1

Overall, the basophil activation test demonstrated the best accuracy at predicting allergic reactions to both baked and fresh milk, with an area under the receiver operator characteristic curve of 0.90 and 0.81, respectively, compared with sIgE (0.75 and 0.74) and a skin prick test (0.70 and 0.78).1

Using cut-offs with 100% sensitivity and specificity, the proportion of children who would undergo a baked milk oral food challenge would be 99% for skin prick testing to baked milk, 82% for SIgE to boiled milk, and 49% for basophil activation test to baked milk. Among those tested, the proportion with a positive result would be 13% for the skin prick test, 17% for sIgE, and 24% for the basophil activation test. This shows that the basophil activation test selects fewer children for testing but identifies a greater percentage of true positives.1

Among children under 2 years, only 27% required an oral food challenge following a basophil activation test to baked milk, compared with 100% following a skin prick test and 81% following sIgE to milk extract. The analysis showed that this finding had 100% diagnostic accuracy.1

“Whether [basophil activation test] brings additional value to existing tests is a wider question that needs to consider other factors, such as availability of tests, access and capacity to do [oral food challenge], acceptable risk and patient preferences,” investigators wrote.1 “Interestingly, the second-best test was different for [baked milk] allergy and for [fresh milk] allergy. For BM allergy, sIgE was better than SPT. For FM allergy, it was the reverse.”

References

1. Bartha I, Boyd H, Foong RX, et al. The Basophil Activation Test Is the Most Accurate Test in Predicting Allergic Reactions to Baked and Fresh Cow's Milk During Oral Food Challenges. Allergy. Published online August 13, 2025. doi:10.1111/all.16675

2. Spolidoro GCI, Ali MM, Amera YT, et al. Prevalence estimates of eight big food allergies in Europe: Updated systematic review and meta-analysis. Allergy. 2023;78(9):2361-2417. doi:10.1111/all.15801