そば主要アレルゲンのImmunoblotting法による検討  [in Japanese] ALLERGEN ANALYSIS OF BUCKWHEAT BY THE IMMUNOBLOTTING METHOD  [in Japanese]

そば過敏症は, そばの摂取によって, ショック, 喘鳴, 呼吸困難, 喉頭浮腫, 蕁麻疹, 腹痛, 嘔吐等の即時型アレルギー症状を呈し, その機序としてI型アレルギーの関与が言われている。筆者らはそば特異的IgE抗体陽性者の血清を用い, immunoblotting法, radioallergosorbent test (以下RAST) 法, RAST inhibition法を行い, そば主要アレルゲンの同定を試みた。immunoblotting法で50%以上の患者のIgE抗体と結合能を示したバンドの分子量は, 67〜70kD, 26kD, 24kDであり, 24kDのバンド (以下BW24KD) が最も陽性率が高かった。RAST法では, そば特異的IgE抗体陽性患者41名中35名 (約85%) がBW24KDに対しても陽性を示し, そば抗原とBW24KDに対する%bindingの間には正の相関 (LogY=0.929LogX-0.689, r=0.92, p<0.001) がみられた。また, RAST inhibition法では, そばとBW24KD間で50%以上の抑制がみられた。以上からBW24KDはそばの主要アレルゲンの1つであると考えられた。またBW24KDは, 分子量の異なる何種類かの蛋白質とheterodimerを形成していると示唆された。

Inhalation or ingestion of very small amounts of buckwheat allergen can initiate severe symptoms including wheezing, rhinorrea, urticaria, vomiting and anaphylactic shock in patients with hypersensitivity against buckwheat. However, few studies of the immunological properties of buckwheat allergen have been made. The aim of the present investigation was to analyze the allergen in buckwheat antigen using the immunoblotting method, radioallergosorbent test (RAST) and RAST inhibition assay. Buckwheat 24 kilodalton protein (BW24KD) was shown by immunoblotting analysis to be the most frequently recogniztd allergenic component, binding to IgE antibodies from 100% of the patients' sera. There was a significant positive correlation (p<0.001) between % bindings for BW24KD and buckwheat. In the RAST inhibition assay using patients' sera which showed positive IgE antibodies to buckwheat and BW24KD, there was effective inhibition in a dose-dependent manner between inhibition in a dose-dependent manner between BW24KD and buckwheat. These data indicated that BW24KD was a major allergen in buckwheat antigens. The experiments of SDS-PAGE using digestion buffer with or without 2-mercaptoethanol suggested that BW24KD was a component of heterodimer and the paired components had different molecular weights.