Basophil activation test in the diagnosis of drug-induced hypersensitivity reactions: a retrospective study of Slovak patients

<b>Background.</b> Drug hypersensitivity reactions (DHRs) include allergic, exaggerated pharmacologic, and pseudoallergic reactions to medications. The basophil activation test (BAT) using CD63 expression is a sensitive and specific complementary tool in the diagnosis of immediate DHRs. <b>Methods.</b> In this study we analysed retrospectively 1160 patients with history of DHRs categorized into several subgroups of diagnoses. BAT using CD63 expression was performed in the whole blood and results were analysed by flow cytometry. <b>Results.</b> The mean value of CD63 expression was significantly higher for positive patients than negative/borderline findings (P ˂ 0.001). The highest frequencies of positive BAT were in categories of diagnosis codes D89 (Other disorders involving the immune mechanism, not elsewhere classified) and L50 (Urticaria). The percentage values were the higher in the group of antibiotics and anticoagulants. Comparing individual drugs <i>in vitro</i>, we observed the highest prevalence of positive reactions by local anaesthetics (Mepivastesin, Mesocain, Lidocaine), antibiotics (Amoxiclav, Megamox duo), antirheumatics, antiphlogistics and antiuratics (Ibuprofen, Ibalgin). The BAT positivity decreases with age, there were significant differences in the CD63 activation between old age and children, younger adults, and older adults (P ˂ 0,001, P ˂ 0,05 and P ˂ 0,01, respectively). No significant differences have been found between men and women. <b>Conclusions.</b> BAT is a useful complementary tool to support the diagnosis of drug hypersensitivity conditions, especially in cases with severe reaction where drug challenge is contraindicated. The implementation of BAT in clinical practice is valuable in the workup of DHRs and extremely useful in the case of life-threatening drug allergies.