D.A. Moneret-Vautrin

The aims of this work were to investigate, in children and adolescents, the clinical aspects of food hypersensitivity and the distribution of allergens, in a prospective and descriptive study. Five hundred and forty-four pediatric cases from a series of 703 patients with food allergies, confirmed by food challenge, were studied. Their clinical characteristics and the distribution according to allergen were investigated. There was a family history of atopic disease in 70.5% of patients. Atopic dermatitis was the main symptom (275/544; 50.5% of patients), followed by urticaria and angio-edema (165/544; 30%). There was asthma in 8.6% of patients (47 children) and anaphylaxis in 4.5% (27 patients). The rarest signs were rhinitis (n=2; 0.3%), oral allergy syndrome (n=8; 1.4%), and gastrointestinal signs (n=11; 2%). Five allergens accounted for 78% of food hypersensitivity. These allergens were: eggs (36%), peanuts (24%), cow's milk (8%), mustard (6%), and cod (4%). Peanut was the most common allergen for children over the age of 3 yr. In this selected population, sensitivity of individuals to more than three foods was unusual (5%). Atopic dermatitis was the main symptom of food allergy in children. The symptoms changed over time, with respiratory disorders, oral allergy syndrome and ocular problems occuring later. Anaphylaxis also occured mostly in older children. Five allergens were responsible for more than three-quarters of food allergies in children. However, the number of allergens implicated was higher for the group of children over the age of 6 yr than for younger children.

For both wheat allergy and coeliac disease the dietary avoidance of wheat and other gluten-containing cereals is the only effective treatment. Estimation of the maximum tolerated amount of gluten for susceptible individuals would support effective management of their disease. Literature was reviewed to evaluate whether an upper limit for gluten content in food, which would be safe for sufferers from both diseases, could be identified. When setting gluten limits for coeliac disease sufferers, the overall potential daily intake should be considered, while for wheat allergy limits should be based on single servings. For coeliac disease sufferers this limit should lie between 10 and 100 mg daily intake. For wheat allergy, lowest eliciting doses for children lie in the lower milligram range, while for adults they are most significantly higher. Gliadins (part of the gluten proteins) not only trigger coeliac disease, but are also major allergens in wheat allergy. Therefore, measurement of gliadins with validated enzyme-linked immunosorbent assay methods provides an appropriate marker for assessing gluten and/or wheat protein contents in food. Available data suggest that a maximum gluten content for 'gluten-free' foods could be set, which protects both wheat allergy sufferers and coeliac patients.

BACKGROUND: While the ingestion of small amounts of an offending food can elicit adverse reactions in individuals with IgE-mediated food allergies, little information is known regarding these threshold doses for specific allergenic foods. While low-dose challenge trials have been conducted on an appreciable number of allergic individuals, a variety of different clinical protocols were used making the estimation of the threshold dose very difficult. OBJECTIVE: A roundtable conference was convened to develop a consensus clinical protocol for low-dose challenge trials for the estimation of threshold doses for specific allergenic foods. METHODS: In May 2002, 20 clinical allergists and other interested parties were invited to participate in a roundtable conference to develop consensus of the key elements of a clinical protocol for low-dose challenge trials. RESULTS: A consensus protocol was developed. Patients with convincing histories of food allergies and supporting diagnostic evidence including past challenge trials or high CAP-RAST scores can be enrolled in low-dose challenge trials. Care must be taken with younger patients to assure that they have not outgrown their food allergy. An approach was developed for the medication status of patients entering such trials. Challenge materials must be standardized, for example, partially defatted peanut flour composed of equal amounts of the three major varieties of peanuts (Florunner, Virginia, Spanish). Challenge materials must be appropriately blinded with sensory evaluation used to confirm the adequacy of blinding. A double-blind, placebo-controlled design should be used for low-dose challenge trials. Low-dose challenge trials would begin at doses of 10 microg of the allergenic food and would continue with doses of 100 microg and 1 mg followed by specific higher doses up to 100 mg depending upon the expert judgement of the physician; even higher doses might be applied to assure that the patient is indeed reactive to the particular food. A 30-min time interval would be used between doses, and reactive doses would be expressed as both discrete and cumulative doses. The goal of each challenge would be to develop objective symptoms; trials should not be discontinued on the basis of subjective symptoms only. Statistically, a minimum of 29 patients would be enrolled in low-dose challenge trials for each allergenic food because 0 reactors out of 29 patients at a particular dose allow the conclusion that there is 95% certainty that 90% of allergic individuals will not react to that dose. CONCLUSION: A consensus protocol was developed. Using this protocol, it will be possible to estimate threshold doses for allergenic foods, the lowest amount that elicits mild, objective symptoms in highly sensitive individuals.

Fourteen patients who had had a life-threatening reaction within a few minutes after receiving propofol (Diprivan) were investigated for anaphylaxis 4-6 weeks after the incident. Three kinds of immunologic tests were carried out: skin tests (prick tests and intradermal tests with the drugs used and Intralipid, the solvent for propofol), a leukocyte histamine release test, and a radioimmunoassay (RIA) of immunoglobulin E (IgE) against propofol and muscle relaxants, when they had been given with propofol. It had been previously shown that these were always negative in patients anesthetized with propofol without any complications. Thirteen of the 14 patients had at least one positive test supporting hypersensitivity to propofol; 2 patients had three tests positive; 4 had two tests positive; and 7 had one test positive. The skin tests with Intralipid were negative in 4 patients whose tests with propofol were positive. Two patients who had been given muscle relaxants at the same time as the propofol had positive IgE-RIA to both drugs. In one patient, results of all the tests remained negative, and the mechanism involved in the reaction remained unidentified. It is note-worthy that 9 patients of 14 had allergic histories that were known before the anesthetic (atopy; allergy to antibiotics, muscle relaxants, lidocaine, colloids) and that none of the patients had ever received propofol or Intralipid before. It is possible that the IgE that linked abnormally with the propofol had specific binding sites for the phenyl nucleus and the isopropyl groups, which are present in propofol and many other drugs.(ABSTRACT TRUNCATED AT 250 WORDS)