The diagnostic usefulness of the basophil activation test (BAT) with annexin V in an allergy to Alternaria alternata.

Background. The basophil activation test (BAT) is an effective diagnostic tool in mold allergy, which is still not sufficiently known. Objectives. The aim of our study was to assess the degree of annexin V binding to the surface of the basophil cell membrane after stimulation with anti-immunoglobulin E (anti-IgE) and Alternaria alternata allergenic extract. Material and methods. Alternaria alternata allergic patients (n = 32) and healthy volunteers (n = 33) were evaluated using skin prick tests (SPT), quantification of specific IgE (sIgE) and the BAT. Basophil activation was detected as a percentage degree of annexin V binding to the surface of the basophil cell membrane. Results. Receiver operating characteristic (ROC) curve analysis yielded a threshold value of 4.95% of activated basophils when the tested group and control group were studied, with a sensitivity and specificity of 100% (area under curve (AUC) = 1; p = 0.00000) for 100 SBU/mL Alternaria alternata allergen extract. The threshold value was 10.28% with a sensitivity of 93.8% and specificity of 100% (AUC = 0.98958; p = 0.00000) for 10 SBU/mL mold extract, and 9.37% with a sensitivity of 90.3% and specificity of 100% (AUC = 0.96307; p = 0.00000) for 1 SBU/mL Alternaria alternata allergen extract. The method was least efficacious in anti-IgE stimulation, where the threshold value was 5.48% with a sensitivity of 90.6% and specificity of 30.3% (AUC = 0.46780; p = 0.67039). Conclusions. The BAT with annexin V and sIgE measurement against Alternaria alternata increase the capability of a diagnostic laboratory for detecting mold sensitization. Both methods may certainly replace SPT, which are currently routinely used in allergy diagnosis. Annexin V may be considered a new basophil activation marker with an efficacy comparable to that of CD63 or CD203c.