The Efficacy of Hazelnut IgE Component Testing in Determining Hazelnut Sensitivity

RATIONALE: Prior studies indicate that hazelnut component testing (HCT) may serve as a better indicator for clinical reactivity than skin prick (SPT) and hazelnut-specific IgE testing (hIgE) in patients with birch pollen allergy. The efficacy of HCT in determining clinical reactivity represents a potential gap in clinical management.

METHODS: A retrospective chart review was performed on six patients who underwent HCT to Cor a 1, 8, 9, and 14. None of the patients ate products containing hazelnut (PCH) at the time of HCT due to prior positive allergy testing with hIgE testing (one patient had positive SPT). Four of the patients reported tolerating PCH prior to allergy testing, one had no exposures, and one developed throat itching upon ingestion. The charts were reviewed for demographic data, birch specific IgE (bIgE), hIgE levels, SPT test results, hazelnut Cor a 1, 8, 9, and 14 levels, and trial of PCH.

RESULTS: Average total IgE=411.11 (SD: 529.07; N: 6), hIgE=15.95 (SD=17.36; N=6), bIGE=9.57 (SD=45.06; N=6), Cor a 1=29.85 (SD=40.16; N=6), Cor a 8=0.1 (SD=1.52; N=6), Cor a 9=0.34 (SD=0.53; N=6), and Cor a 14=0.27 (SD=0.27; N=6). Five of six patients introduced PCH into their diet. Their average Cor a 1=35.80 (SD=41.84; N=5) and Cor a 9=0.12 (SD=0.06; N=5) versus the one patient who did not introduce PCH (Cor a 1=0.1 and Cor a 9=1.43).

CONCLUSIONS: This was a pilot study undertaken to investigate the utility of HCT. This study suggests that HCT can determine clinical reactivity in birch pollen allergic patients with positive hIgE.