The utility of the basophil activation test in differentiating asthmatic subjects with and without allergic bronchopulmonary aspergillosis.

BACKGROUND: Asthma with Aspergillus sensitization (ASA) and allergic bronchopulmonary aspergillosis (ABPA) are distinct clinical conditions, with different management strategies.

OBJECTIVE: To determine the utility of the basophil activation test (BAT) in differentiating between asthmatic subjects with and without ABPA.

METHODS: We performed the BAT using flow cytometry for the basophil activation markers CD63, CD193, and CD203c in consecutive subjects with unsensitized asthma (UA), ASA, and ABPA. The BAT was performed unstimulated (baseline) and after stimulation with peanut and Aspergillus fumigatus antigens. Stimulation indices (SI) for CD63, CD193, and CD203c were compared between the study groups.

RESULTS: We enrolled 82 (UA [n=25], ASA [n=25], ABPA [n=32]) subjects. Only those subjects without peanut sensitization on serological testing were included in further analyses (n=50). The receiver operating characteristic analysis of SI for CD63, CD193, and CD203c for the diagnosis of ABPA versus other asthmatics (UA and ASA) showed an area under the curve of 0.577, 0.317, and 0.625, respectively. The SI CD203c at a cut-off of 1.2 (sensitivity 50.0%, specificity 88.9%) and the SI CD63 at a cut-off of 1.3 (sensitivity 42.9%, specificity 91.7%) also had limited utility for the diagnosis of ABPA.

CONCLUSION: The BAT cannot be used as a diagnostic test in distinguishing ABPA complicating asthma from ASA and UA.