National Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
Int Arch Allergy Immunol. 2012;159(2):209-12. doi: 10.1159/000336027. Epub 2012 Jun 1.
Diagnosis of peanut allergy has improved thanks to component-resolved diagnostics. Peanut allergen component Ara h 2 is considered to indicate true peanut allergy. The component Ara h 6 is structurally similar to Ara h 2, but the diagnostic value of analyzing IgE antibodies to Ara h 6 is unclear. A boy sensitized (≥0.35 kU(A)/l) to Ara h 8 but not to Ara h 1, Ara h 2 and Ara h 3 was challenged with peanut and developed grade II anaphylaxis. In serum collected at the time of challenge a doubling of IgE to the peanut allergen extract was observed compared to allergy testing 9 months earlier. In contrast, IgE levels to Ara h 1, Ara h 2, Ara h 3 and to Ara h 8 were rather unchanged. After another 2 months, Ara h 6 was analyzed and revealed a level of 24 kU(A)/l whilst Ara h 2 was 0.12 kU(A)/l. We suggest that IgE sensitization to Ara h 6 caused the reaction and conclude that analyses of IgE levels to peanut and peanut components should be performed in connection with a challenge. Furthermore, levels to Ara h 2 below 0.35 kU(A)/l may still indicate a risk of severe reaction at the time of challenge since in rare cases, Ara h 6 IgE antibodies may be present without occurrence of IgE antibodies to Ara h 2.
由于成分解析诊断，花生过敏的诊断得到了改善。花生过敏原成分 Ara h 2 被认为可指示真正的花生过敏。Ara h 6 与 Ara h 2 在结构上相似，但分析 IgE 抗体对 Ara h 6 的诊断价值尚不清楚。一名男孩对 Ara h 8 （≥0.35 kU(A)/l）致敏，但对 Ara h 1、Ara h 2 和 Ara h 3 不致敏，他接受了花生挑战，出现了 II 级过敏反应。与 9 个月前的过敏测试相比，在挑战时采集的血清中观察到对花生过敏原提取物的 IgE 增加了一倍。相比之下，IgE 水平对 Ara h 1、Ara h 2、Ara h 3 和 Ara h 8 几乎没有变化。2 个月后，分析了 Ara h 6，发现其水平为 24 kU(A)/l，而 Ara h 2 为 0.12 kU(A)/l。我们认为，Ara h 6 的 IgE 致敏引起了反应，并得出结论，在进行挑战时，应进行花生和花生成分的 IgE 水平分析。此外，Ara h 2 的水平低于 0.35 kU(A)/l仍可能表明在挑战时发生严重反应的风险，因为在极少数情况下，可能存在 Ara h 6 IgE 抗体而不存在 Ara h 2 IgE 抗体。
