Werfel S J, Cooke S K, Sampson H A
Department of Pediatrics, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
J Allergy Clin Immunol. 1997 Mar;99(3):293-300. doi: 10.1016/s0091-6749(97)70045-9.
Cow's milk is one of the most common food allergens in children. Limited information is available on the prevalence of reactivity to a related food source, beef. The purposes of this study were to examine the prevalence of symptomatic sensitivity to beef in a selected pediatric population and to determine the frequency of concomitant reactivity to cow's milk and beef.
Children referred for assessment of atopic dermatitis and possible food hypersensitivity were evaluated for symptomatic reactivity to beef by double-blind placebo-controlled food challenges (DBPCFCs) and subsequent open feedings of beef. Sodium dodecyl-sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), immunoblot, and immunodot blot analyses were performed with patients' sera on preparations of beef extracts subjected to different cooking conditions: raw (no heating), medium, and well-cooked.
Eleven of 335 children referred for evaluation of atopic dermatitis and possible food hypersensitivity were found to have symptomatic sensitivity to beef; eight were also sensitive to milk, as demonstrated in previous DBPCFCs. Eight patients reacted to beef during DBPCFC, and three tolerated beef in a DBPCFC and well-cooked beef in an open challenge but reacted to ingestion of less well-cooked beef. SDS-PAGE of raw beef revealed at least 24 protein fractions. Several protein bands in raw beef appeared to denature with heating. Bovine serum albumin and bovine gamma globulin were heat-labile in the beef extract, but six protein fractions persisted even after heating the beef extract for 2 hours at 85 degrees C. IgE from patients reacting to rare and well-cooked beef bound up to six of these heat-resistant fractions, but IgE from patients reacting only to rare beef failed to bind any of these fractions with one exception. In addition, patients reacting to rare and well-cooked beef had specific IgE to a 17.8 kd fraction, which was only weakly recognized by one patient reacting only to rare beef.
Specific IgE antibodies to heat-labile beef proteins might explain why some patients can tolerate well-cooked beef but not medium-rare and rare beef. Patients reacting only to rare beef may not need to maintain a complete beef elimination diet.
牛奶是儿童中最常见的食物过敏原之一。关于对相关食物来源牛肉产生反应的患病率的信息有限。本研究的目的是调查特定儿科人群中对牛肉有症状性敏感的患病率，并确定对牛奶和牛肉同时产生反应的频率。
对因特应性皮炎评估和可能的食物过敏而转诊的儿童，通过双盲安慰剂对照食物激发试验（DBPCFC）以及随后的牛肉开放喂养，评估其对牛肉的症状性反应。用患者血清对经过不同烹饪条件（生肉（未加热）、五分熟、全熟）的牛肉提取物制剂进行十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）、免疫印迹和免疫斑点印迹分析。
在335名因特应性皮炎评估和可能的食物过敏而转诊的儿童中，有11名被发现对牛肉有症状性敏感；如先前的DBPCFC所示，其中8名对牛奶也敏感。8名患者在DBPCFC期间对牛肉有反应，3名患者在DBPCFC中能耐受牛肉，在开放激发试验中能耐受全熟牛肉，但对食用不太熟的牛肉有反应。生牛肉的SDS-PAGE显示至少有24个蛋白组分。生牛肉中的几个蛋白条带似乎随着加热而变性。牛肉提取物中的牛血清白蛋白和牛γ球蛋白对热不稳定，但即使在85℃将牛肉提取物加热2小时后，仍有6个蛋白组分存在。对生牛肉和全熟牛肉有反应的患者的IgE能与这些耐热组分中的多达6个结合，但仅对生牛肉有反应的患者的IgE除一个例外未能与这些组分中的任何一个结合。此外，对生牛肉和全熟牛肉有反应的患者对一个17.8kd的组分有特异性IgE，而仅对生牛肉有反应的一名患者对该组分的识别较弱。
对热不稳定牛肉蛋白的特异性IgE抗体可能解释了为什么一些患者能耐受全熟牛肉但不能耐受五分熟和生牛肉。仅对生牛肉有反应的患者可能无需维持完全避免食用牛肉的饮食。
