Basophil activation test can diagnose asthma in young children

Despite the prevalence of asthma among children, there are currently no reliable biomarkers available to diagnose the disease and its severity in young children.

Researchers at Shanghai Jiao Tong University School of Medicine and Shanghai Children’s Medical Center sought to determine with greater confidence whether using the CD63 basophil activation test (BAT) can differentiate asthma from other causes of respiratory illness in young children with wheezing episodes.

Their study, “Utility of basophil activation test for predicting the outcome of wheezing in children: a pilot study,” was published in the journal BMC Immunology in January 2021.

By assessing the expression level of molecules on the surface of basophils, a type of white blood cell involved in allergic diseases such as asthma, after exposure to allergens, the CD63-BAT can be used to assess the extent of basophil activation.

Recent research has indicated that CD63-BATs are helpful in the clinic for identifying allergies to medications, foods, and other substances with a high level of sensitivity and specificity, and that the tests can also be used to monitor the severity of allergies and the responsiveness of patients to allergen immunotherapies.

In the present study, Dr. Jinyang Li and his team took these data a step further and performed a prospective cohort study to determine BAT’s clinical relevance in predicting the severity of asthma in children.

BATs were performed using patient samples stimulated with a mixture of inhalant allergens and the test results were based on the CD63 activation marker, expressed on the surface of basophils.

Positive BAT results were defined as those involving the upregulation of CD63 by at least 15% over baseline after stimulation with inhalant allergens. A total of 38 patients under the age of 5 completed the BAT.

After a 2-year follow-up period, 26 patients were diagnosed with asthma, and 17 were diagnosed with bronchiolitis or viral-induced wheezing.

The positive BAT result was significantly higher for children diagnosed with asthma than those not diagnosed with asthma (85.2% compared to 18.2%, respectively).

Although the asthma predictive index (API) has been used on young, wheezing children, the sensitivity and specificity of API are limited, especially when wheezing is less frequent.

However, despite the low frequency of wheezing in the current study’s subjects, the performance of the CD63-based BAT for predicting asthma diagnosis was similar to that of the API.

The sensitivity, specificity, positive predictive value, and negative predictive value of the API in predicting asthma outcome for the subjects were 88.9, 45.5, 80.0, and 62.5%, respectively while the CD63-based BAT were 85.2, 50.0, 71.8, and 69.2%, respectively.

This study demonstrated not only that BAT has clinical relevance for the diagnosis of asthma in children, but also that CD63 is a useful biomarker for assessing basophil activation in the context of the disease.

As such, this study showed a potential biomarker for the prediction of early diagnosis of asthma in young children.

However, more comprehensive research incorporating a greater number of patients and a longer follow-up time should be conducted, as this study had a relatively limited sample size (38 at second follow-up) and follow-up time (2 years).

Additionally, further studies could help to determine the efficacy of other biomarkers for diagnosing and monitoring asthma in children.

Read about the latest research in the field of immunology from ImmunoFrontiers.

Li J, Wu J, Liu H et al. (2021) Utility of basophil activation test for predicting the outcome of wheezing in children: a pilot study. BMC Immunol, (22)4.