研究分析低過敏配方奶對於過敏活性的影響

作者：Jacquelyn K. Beals, PhD  
出處：WebMD醫學新聞

　　December 14, 2009 (阿根廷布宜諾斯艾利斯) — 根據水解牛奶或併用胺基酸的低過敏配方，在生化與免疫特徵上各有不同。使用十二烷基硫酸鈉聚丙烯醯胺膠體電泳(SDS-PAGE)、質譜儀、免疫球蛋白(Ig)E反應性等，測量和確認每種配方的低過敏程度。
　　
　　根據奧地利維也納醫學大學、醫學與化學實驗診斷研究中心博士候選人Heidrun Hochwallner小姐在世界過敏組織第21屆世界過敏研討會發表她們的研究時所述，第1年時，2%- 3%的嬰兒對牛奶發生過敏，這通常是與提早使用牛奶有關。對於可能過敏的孩童，通常使用不含過敏原的配方或者不會造成產生有害之細胞激素的配方來預防牛奶的致敏作用和過敏。
　　
　　科學家們研究牛奶蛋白質將近50年，指出提早使用牛奶的小孩比較可能會發生敏感性，因為半數以上的過敏孩童並無家族過敏史，預防牛奶過敏的一個有效方法是對所有需要補母乳量不足的孩童使用水解牛奶蛋白質。
　　
　　目前的研究針對16種牛奶配方，探討它們各自的過敏活性。對22名牛奶過敏的病患血清檢測每種配方的IgE反應性；從牛奶過敏病患與對牛奶有IgG抗體者的週邊血液單核細胞，培養檢測T細胞分化與細胞激素分泌。
　　
　　Hochwallner小姐向Medscape Allergy and Immunology表示，在檢測的16種配方中，胺基酸配方之IgE鍵結活性、T細胞反應性最低，過敏性也低。她表示，相對的，含有完整蛋白質的配方，IgE鍵結活性、T細胞反應性與過敏性最高。
　　
　　Hochwallner小姐表示，我們在細胞激素值的誘發上也發現有差異，所以我們可以區別確認誘發較少干擾素-γ、干擾素-α、與介白素([interleukin] IL)-6等的配方。而且，我們可以發現誘發較少Th2驅動之細胞激素、IL-5和IL-13的配方。
　　
　　如同會議摘要中所總結的：我們可以根據過敏活性將各種配方排序，最有趣的是，我們可以指出哪些配方不會刺激可能的有害細胞激素，意指這些配方不只沒有IgE相關發炎與過敏活性，也不會誘發產生有害的細胞激素。
　　
　　會議共同主持人、路易西安納州大學健康科學中心、過敏與免疫訓練計畫主任、過敏與免疫主任、小兒科與內科教授、Sami Bahna博士向Medscape Allergy and Immunology表示，這是否表示「低過敏性牛奶配方」標準多變？這有點令人驚訝，但實際上不然，是因為每個製造商的製程差異。
　　
　　Bahna博士表示，分子或胜肽相當多變，例如，完全水解的乳清中仍可能有酪蛋白，因為乳清是由全乳製成。酪蛋白製成的配方中會含有乳清，不過，它們一般是低過敏性的，對牛奶過敏的孩童只有約3%-5%對完全水解配方過敏。
　　
　　Bahna博士表示，另一方面，部份水解配方有較大的胜肽，會引起過敏。因此，雖然可能可以預防過敏，但是並不適用，事實上，它們禁用於已經過敏的孩童。對牛奶或配方奶過敏的人必須使用完全水解配方，市面上或許有超過95%的配方是耐受良好的。Bahna博士指出，如果無法耐受，就改用胺基酸配方。
　　
　　Bahna博士解釋，而且，與有無貨源、社會、社區及價位等因素有關。多數對牛奶過敏的孩童可耐受豆奶配方，價位差不多，但是比較容易取得，味道也可以接受。如果是高過敏性病患，我們必須個別化處理，必須使用比較貴的配方或胺基酸配方，這種個別化方式對家庭來說比較好。
　　
　　發表者在結語時指出一些沒有IgE相關發炎與過敏活性、也不會誘發產生有害細胞激素的配方。作者們認為，其他類型的發炎型疾病，如發炎性腸道疾病，也可能從這些非發炎配方奶中獲得相關幫助。
　　
　　Hochwallner小姐以及Bahna博士皆宣告沒有相關財務關係。
　　
　　世界過敏組織第21屆世界過敏研討會(WAC)：摘要471。發表於2009年12月7日。


Study Analyzes "Hypoallergenic" Cow's Milk Formulas for Allergenic Activity

By Jacquelyn K. Beals, PhD
Medscape Medical News

December 14, 2009 (Buenos Aires, Argentina) — Hypoallergenic formulas based on hydrolyzed cow's milk or combinations of amino acids have considerable variation in their biochemical and immunologic characteristics. The degree to which a given formulation is hypoallergenic can be identified and measured with sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), mass spectrometry, and the immunoglobulin (Ig)E reactivity of each formula.

During their first year, 2% to 3% of infants develop hypersensitivity to cow's milk. This is frequently associated with early exposure to cow's milk. Formulas that lack allergenic activity and do not lead to harmful cytokine production are useful for preventing cow's milk sensitization and allergy in potentially sensitive children, according to Heidrun Hochwallner, a PhD candidate at the Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Vienna, in Austria, who presented her team's research here at the World Allergy Organization XXI World Allergy Congress.

Scientists have investigated milk proteins for nearly 50 years, and note that sensitivity is more likely to occur in children with early exposure to cow's milk. Because more than half of allergic children have no family history of allergy, an effective way to prevent milk allergies might be to use hydrolyzed milk protein for all children who require breast milk supplements.

The current study investigated 16 cow's milk formulas to determine their respective allergenic activity. The IgE reactivity of each formula was tested in sera from 22 patients with a cow's milk allergy; T-cell proliferation and cytokine secretion were examined in cultures of peripheral blood mononuclear cells from patients with cow's milk allergy and from people with IgG antibodies specific to cow's milk.

Among the 16 formulas tested, "the amino acid formulations showed the lowest IgE-binding activity, low T-cell reactivity, and low allergenic activity," Ms. Hochwallner told Medscape Allergy and Immunology. In contrast, "the formulas with intact proteins, complete proteins, showed high levels of IgE-binding activity, T-cell reactivity, and allergenic activity," she said.

"We could also see a difference in the induction of cytokine levels, so we could kind of identify formulas that induce lower levels than others of interferon-γ, interferon-α, and [interleukin] IL-6.?.?.?. And we could see formulas that induced lower levels of the Th2-driving cytokines IL-5 and IL-13," said Ms. Hochwallner.

As summarized in the meeting abstract: "We could rank the various formulas regarding allergenic activity. Most interestingly, we could demonstrate that certain formulas did not stimulate a potential detrimental cytokine pattern, indicating that these formulas not only lack IgE-related inflammatory and sensitizing activity, but also do not induce harmful cytokine production."

Is it odd that the standards for "hypoallergenic cow's milk formulas" are so varied? It is "somewhat surprising, but not really, because the manufacturing process varies from one manufacturer to another," session comoderator Sami Bahna, MD, DrPH, professor of pediatrics and medicine, chief of allergy and immunology, and director of the Allergy and Immunology Training Program, Louisiana State University Health Sciences Center, in Shreveport, told Medscape Allergy and Immunology.

"The molecules or the peptides that are remaining can vary widely — for example, the extensively hydrolyzed whey. You may find casein in it, because the whey came from the whole milk," said Dr. Bahna. "Casein-derived formulas can have whey in them, but generally, they are hypoallergenic. Only about 3% to 5% of children who are allergic to cow's milk are allergic to the extensively hydrolyzed formula."

"On the other hand, partially hydrolyzed formulas have larger peptides and can cause allergy. So although they are useful as?.?.?. prophylaxis, they are not indicated. In fact, they are contraindicated for children who are already allergic," Dr. Bahna said. A person who is truly allergic to cow's milk or milk formula has to go to extensively hydrolyzed formula, and probably more than 95% of the formula on the market would be tolerated well. "If it's not tolerated, then they go to amino acid formulas," added Dr. Bahna.

"Also, it depends on the availability, the society, the community, and the prices," explained Dr. Bahna. "The majority of cow's-milk-allergic children would tolerate soy formula, which is similar in price, and it's easily available and the taste is reasonable also. We have to individualize," Dr. Bahna said. "If a person is highly allergic, we may have to go to the very expensive or the amino acid formulas?.?.?. so the individualization will be good for the family."

In closing, the presenters noted that some formulas lack IgE-related inflammatory and sensitizing activity and do not induce production of harmful cytokines. The authors suggest that other types of inflammatory disease — inflammatory bowel disease, for example — might benefit from these noninflammatory milk formulations.

Ms. Hochwallner and Dr. Bahna have disclosed no relevant financial relationships.

World Allergy Organization XXI World Allergy Congress (WAC): Abstract?471. Presented December?7, 2009.