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Oral allergy syndrome or OAS is a type of food allergy classified by a cluster of allergic reactions in the mouth in response to eating certain (usually fresh) fruits, nuts, and vegetables that typically develops in adults with hay fever. OAS is perhaps the most common food-related allergy in adults. OAS is not a separate food allergy, but rather represents cross-reactivity between distant remnants of tree or weed pollen still found in certain fruits and vegetables. Therefore, OAS is typically only seen in tree and weed allergic patients, and is usually limited to ingestion of only uncooked fruits or vegetables.〔The Online Allergist, Retrieved 2010-10-10〕 Another term used for this syndrome is pollen-food allergy. In adults up to 60% of all food allergic reactions are due to cross-reactions between foods and inhalative allergens. OAS is a Type 1 or IgE-mediated immune response, which is sometimes called a "true allergy". The body's immune system produces IgE antibodies against pollen; in OAS, these antibodies also bind to (or cross-react with) other structurally similar proteins found in botanically related plants. OAS can occur any time of the year but is most prevalent during the pollen season. Individuals with OAS usually develop symptoms within a few minutes after eating the food.〔(【引用サイトリンク】title=OAS Information )〕 == Signs and symptoms == OAS sufferers may have any of a number of allergic reactions that usually occur very rapidly, within minutes of eating a trigger food. The most common reaction is an itching or burning sensation in the lips, mouth, ear canal, and/or pharynx. Sometimes other reactions can be triggered in the eyes, nose, and skin. Swelling of the lips, tongue, and uvula and a sensation of tightness in the throat may be observed. It can seldom result in anaphylaxis. If a sufferer swallows the food, and the allergen is not destroyed by the stomach acids, there is a good chance that there will be a reaction from histamine release later in the gastrointestinal tract. Vomiting, diarrhea, severe indigestion, or cramps may occur. Rarely, OAS may be severe and present as wheezing, vomiting, hives and low blood pressure.〔(【引用サイトリンク】title= Oral Allergy Syndrome )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「oral allergy syndrome」の詳細全文を読む スポンサード リンク
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