Objective
The purpose of this study is to document clinical utility of measurement of specific IgE antibody to Ara h 2 (Ara h 2-IgE) for diagnosis of peanut allergy in Japanese children.
Methods
One hundred and fifty two children were included having a suspicion of peanut allergy (peanut allergy: PA n=68, non-peanut allergy: NPA n=84). Specific IgE antibodies to five allergen components from peanut in the sera from those subjects were measured by ImmunoCAP^®.
Results
Ara h 2-IgE was the best for diagnosis of peanut allergy. The specific IgE titer of 95% PPV was 4.71 U_A/ml. Sensitivity at that IgE titer was 57.4%. For specific IgE antibody to crude peanut extract (f13-IgE), sensitivity at 50.8 U_A/ml (95% PPV) was 20.6% and that at 14.0 U_A/mL, which was the decision point for 95% PPV reported by Sampson, was 36.8%, respectively. NPV of Ara h 2-IgE at the existing cut off (0.35 U_A/ml) was 89.3% regardless of specific IgE titer of f13.
Conclusion
The measurement of Ara h 2-IgE combined with f13-IgE is accurate for diagnosis of peanut allergy and is useful in order to decrease the number of peanut challenges at the clinic.