Methods: Thirty patients (ages 2-20 years) with a history of SFA were evaluated by OFC. SPT was performed with a commercially available or a high-concentration (HC-sesame) extract prepared from reduced-fat sesame flour (100mg/ml). Induced CD63 expression after exposure to 1mg/ml sesame protein was assessed in the Basophil activation test (BAT). Empirical receiver operating characteristic (ROC) analysis was used to determine the critical values for optimized test performance.
Results: Positive OFC was observed in 20/30 patients (eliciting dose range: 15-4000mg, median: 240mg). BAT (CD63%) and HC-sesame SPT (wheal in mm) mean values differed significantly between the OFC positive and OFC negative groups (BAT: 33.5% vs. 1.4%, p<0.0001; HC-sesame SPT: 13.7mm vs. 5mm, p<0.0001 by Student's two-tailed t-test). ROC analysis of HC-sesame SPT demonstrated at a ≥9mm wheal, a specificity and sensitivity of 80% and 95%, respectively, while a wheal >12mm was 100% specific, with 55% sensitivity. The commercially available extract at ≥3mm wheal, gave a specificity and sensitivity of 30% and 75%, respectively. For BAT, 100% specificity was reached at >6% CD63 induction, yielding 80% sensitivity. All four OFC positive patients with CD63 levels ≤6% had HC-sesame SPT wheals ≥12mm.
Conclusions: In situations that preclude the administration of OFC, the combination of SPT and BAT may predict clinical reactivity.