Food reactions in pollen and latex allergic patients

Untoward allergic reactions to foods may be easily recognized when the clinical symptoms occur immediately. Symptoms occur from very small quantities of food, often within minutes, but sometimes within 1-2 h of eating the suspected food. The clinical responses are urticaria, rhinitis, asthma, vomiting, diarrhoea or anaphylaxis. The diagnosis is easy because of the close correlation between eating the food, and the subsequent symptoms. Moreover, patients with immediate, and often very severe, allergic symptoms from small amounts of food have an IgE-triggered mechanism which can be confirmed by skin or in vitro testing, but immunological symptoms often cannot be demonstrated in a second type of food reaction that occurs at least 2 h, and sometimes even longer than a day, after the ingestion of the offending food(s). These 'delayed' symptoms, while they may be those associated with classical allergy, can also include a wide variety of symptoms affecting various organs. Food 'intolerance' is a word to indicate that, although immune mechanisms may be operative, a definite diagnosis can only be proved with a suitable food challenge. Adverse food reactions in patients with pollen-allergic respiratory disease have been studied during the last 20 years, particularly in the Scandinavian countries, because silver birch (Betula) pollen allergy is the pollen that causes most seasonal allergic complaints, but is also associated with IgE-mediated symptoms related to fresh fruit and vegetables. Skin tests will confirm the cause of symptoms in patients suffering from pollenosis. Allergic crossreactivity among grass pollens is well recognized, since the reactions occur between taxonomically-related grass pollens, but patients often react on skin testing to different unrelated pollens from grasses, weeds and trees which may have no clinical importance. A report in this issue of the Journal begins to explain the allergic relationship between taxonomically-diverse pollens. (DBO)