Basophil Activation Test Shows Poor Sensitivity in Immediate Amoxicillin Allergy

Area of Science:

• Allergy and Immunology
• Diagnostic Medicine
• Immunopathology

Background:

• Accurate diagnosis of amoxicillin (AX) allergy is crucial due to widespread misdiagnosis.
• Current diagnostic methods like skin tests and IgE assays are not fully predictive, sometimes necessitating risky drug challenges.
• There is a need for safe in vitro diagnostics to aid in AX allergy diagnosis.

Purpose of the Study:

• To evaluate the clinical reliability of the basophil activation test (BAT) for amoxicillin (AX) allergy.
• To determine the optimal role of BAT in the diagnostic algorithm for AX allergy.

Main Methods:

• The basophil activation test (BAT) was conducted on 70 control individuals and 66 patients diagnosed with AX allergy.
• Flow cytometry was used to assess the upregulation of CD63 and CD203c markers following AX stimulation.
• Optimal stimulation concentrations and positivity thresholds for CD63 and CD203c were determined.

Main Results:

• The most discriminative concentrations for CD63 and CD203c upregulation were 1370 μmol/L and 685 μmol/L, respectively.
• A diagnostic threshold of 9% positivity was identified for both markers.
• Sensitivity and specificity for CD63 were 13% and 100%, while for CD203c they were 23% and 98%.

Conclusions:

• The basophil activation test (BAT) using dual CD63 and CD203c analysis demonstrates poor performance for diagnosing amoxicillin allergy.
• The low sensitivity of BAT prevents it from playing a significant role in the diagnostic workup of amoxicillin allergy.