Abstract
We investigated usefulness of the basophil activation test (BAT) in predicting the outcome of sting challenge in bee venom-allergic patients after VIT. Twenty-one patients with bee venom anaphylaxis at the end of VIT and 6 control participants were enrolled.
BAT (flow-cytometric evaluation of allergen-induced expression of CD63), skin testing, and specific immunoglobulin (Ig) E determination were performed prior to sting challenge. Five of the 21 patients (23.8%) reacted to sting challenge.
At a bee venom concentration of 100 ng/mL, the mean proportion of basophils expressing CD63 was 56% in reactors and 13.2% in nonreactors (P = .0321). Four of the 5 reactors had positive results and 14 of the 16 nonreactors had negative results.
Thus, using 18.4% and 21.6% (receiver operating characteristic curve analysis) as the cutoff for expression of the CD63 marker, the positive and the negative predictive values were 67% and 93%, respectively, and specificity and sensitivity for BAT were 80% and 83%, respectively. However, at a concentration of 1000 ng/mL, no significant differences in basophil activation were observed between reactors and nonreactors.
We found BAT to be a helpful tool in predicting the clinical sensitivity of bee venom-allergic patients after VIT (correlation between BAT at submaximal venom concentration and sting challenge).