Evaluation of an in vitro mast cell degranulation test in the context of food allergy to wheat

BACKGROUND

Antigenic profiles obtained by ELISA with IgE from patients with wheat food allergy (WFA) established that major allergens are albumins/globulins (AG) for children suffering from atopic eczema/dermatitis syndrome (AEDS), omega5-gliadins for adults suffering from wheat-dependent exercise-induced anaphylaxis (WDEIA), anaphylaxis or urticaria and low-molecular-weight (LMW) glutenin subunits for patients with anaphylaxis. We aimed to characterize a new mast cell transfectant for its ability to degranulate with wheat proteins and patient sera and compare these results to those obtained by ELISA.

METHODS

Thirty sera from patients with WFA were tested: 14 with AEDS (group 1) and 16 with WDEIA, anaphylaxis or urticaria (group 2). An IgE Fc receptor (FcepsilonRI) humanized rat RBL-2H3 line was established by transfection with cDNAs encoding alpha-, beta- and gamma-subunits for the human IgE receptor.

RESULTS

A humanized RBL clone was selected for its capacity to express mRNA alpha-, beta- and gamma-subunits of FcepsilonRI, to bind allergen-specific human IgE and to degranulate. In group 1, sera induced enhanced degranulation with AG extract, but rarely reacted with gliadins and glutenins. In group 2, half of the sera showed degranulation with LMW glutenins whereas the AG fraction and lipid transfer proteins were rarely positive. omega5-Gliadins did not appear as a major allergen in degranulation assays, although functional allergen-specific IgE was measurable in appreciable amounts.

CONCLUSION

Our data demonstrate that in wheat food allergen evaluation, correlation exists between mast cell degranulation and IgE measurements, depending on the type of allergen. Therefore, the biological activity of some allergen types may also be affected by other parameters.

Oral desensitization in children with milk and egg allergies obtains recovery in a significant proportion of cases. A randomized study in 60 children with cow's milk allergy and 90 children with egg allergy

BACKGROUND

Food allergy is treated by avoidance diets in order to prevent anaphylactic reactions and to cure chronic associated symptoms. However, the natural history is left unchanged.

OBJECTIVE

To search for a beneficial effect of an oral desensitization protocol to allergenic foods in IgE-dependent milk or egg allergies in children.

METHODS

60 children with documented cow's milk allergy (13 months-6.5 years), and 90 children with egg allergy (12 months-8 years), were consecutively included after 6-12 months of avoidance diet, if a SBPCFC to 60 ml milk (60 ml) or to 965 mg of raw egg white was negative. They were randomized for uninterrupted avoidance or oral desensitization (group A or OD). Six months later, a new SBPCFC was performed with, up to 200 ml of milk or 7g of raw egg white. Prick tests and specific IgE levels were carried out simultaneously.

RESULTS

Data were obtained for 57 children with CMA (30 A and 27 OD), and 84 children with EA (35 A and 49 OD). The two groups (AD or OD group) were similar with regard to means of ages, the size of PT wheals and the level of IgEs at baseline. MILK ALLERGY: A SBPCFC to milk was positive in 11.1% of those following OD vs. 40% after A (p < .025). The size of PT decreased after OD and increased after A (-3.4 mm vs. +0.84 mm; p < .002). EGG ALLERGY: The SBPCFC to egg was positive in 30.6% after OD vs. 48.6% after A (p < .1). After 6 months, in the OD group, the mean size of the PT and the level of specific IgE were significantly reduced compared to the A group. In the A group, the threshold of reactivity was often lower, or more serious symptoms were observed.

CONCLUSION

Oral desensitization helps the egg and milk allergic children to overcome their allergies. Since the avoidance of these foods is likely to increase sensitization as well as to lower the threshold of reactivity, an active treatment is required. Further attempts to standardize the procedures of oral desensitization are expected.

Risk of allergy to food proteins in topical medicinal agents and cosmetics

The risk of allergy to food proteins in cosmetics and topical medicinal agents is poorly evaluated. IgE dependent contact urticaria and contact dermatitis are observed. Eleven cases (7 infants and 4 women) are reported. Wheat, egg, oats, milk, peanut proteins are incriminated by prick-tests or atopy patch-tests. Cases are related to a previous food allergy and other ones may indicate primary sensitization to topical creams mainly used for skin care of atopic dermatitis. A consecutive exercise induced anaphylaxis to wheat and a long lasting sensitization to wheat have been observed. A clear and accurate identification of food allergens in cosmetics and topical agents is necessary. Given the hyper-permeability of infant skin, topical products containing food proteins of known allergenicity are contra-indicated for neonates, and for infants with atopic dermatitis, which may be associated with skin hyper-permeability.

Collagenous colitis: possible link with isotretinoin

A case of collagenous colitis in a young man treated by isotretinoïn raises the hypothesis of an isotretinoïn inducedcess on the oossible account of atoov and auto-immunity in the family.

Identification of oleosins as major allergens in sesame seed allergic patients

BACKGROUND

The prevalence of sesame allergy is increasing in European countries. Cases of severe allergy lack any evidence of specific immunoglobulin (Ig)Es by prick tests and CAPSystem-FEIA. The reasons for this negativity are unknown.

METHODS

In 32 patients displaying immediate symptoms such as anaphylactic shock, asthma, urticaria, angioedema, sesame allergy was diagnosed by double-blind placebo-controlled food challenge (DBPCFC) or convincing clinical history. However, 10 patients had negative prick tests and CapSystem-FEIA. The specificity of IgEs was further investigated by enzyme-linked immunosorbent assay (ELISA), isoelectrofocalisation (IEF)-blotting, and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) blotting using total sesame extracts and purified fraction of oil bodies. Monospecific rabbit antibodies directed to two oleosin isoforms (15 and 17 kDa) were used.

RESULTS

By ELISA, white sesame seed extract allowed the detection of higher levels of IgE than brown sesame extract. In all sera, numerous bands binding IgEs were detected by IEF or SDS-PAGE. In reducing conditions, two bands (15-17 kDa), could be separated from 2S albumin. Oleosins, present in oil bodies fractions, were recognized by IgEs from all sera.

CONCLUSION

Oleosins are major allergens of sesame seeds and may be relevant to severe anaphylaxis. Falsely negative prick tests could be due to the lack of oleosins in presently available extracts, or to the fact that epitopes might be buried in the inner molecule. Detection tests currently used to identify sesame allergens based on sesame vicillins or other storage proteins could be insufficient for the detection of sesame seed contamination. Oleosins have been named Ses i 4 (17 kDa) and Ses i 5 (15 kDa), in accordance with the IUIS Nomenclature Committee.

Food-dependent exercise-induced anaphylaxis--update and current data

Exercise-induced anaphylaxis (EIA) is defined as the onset of allergic symptoms during, or immediately after, exercise, the clinical signs being various degrees of urticaria, angioedema, respiratory and gastrointestinal signs and even anaphylactic shock. Food-dependent exercise-induced anaphylaxis (FDEIA) introduces food in the syndrome and is revealed by a chronological sequence in which food intake, followed by exercise, induces symptoms after a varying period. When the food intake and the exercise are independent of each other, there are no symptoms. FDEIA is not very frequent. Identifying the culprit food allergen depends on the patient's eating habits. Crustaceans and wheat flour are the two commonest but others foods can be implicated. The patho-physiology of FDEIA has not been clearly established but it appears to result from degranulation of mast cells. As with food allergy, FDEIA diagnosis is based on interview, skin and biological tests and challenge. For the clinical signs of allergy, antihistamines, corticosteroids and epinephrine may be administered. Prophylaxis aims to prevent a recurrence; the patient should be given an emergency kit to deal with any recurrent episode. After the food allergen has been identified, it should be avoided for at least 4 to 5 hours before any exercise.

The risk of systemic reactions to skin prick-tests using food allergens: CICBAA data and literature review

Prick-tests to foods are usually carried out as the first step in the diagnosis of food allergy. Severe anaphylaxis accounts for 4.9 % of allergies in children and occurs more frequently in adults, raising the possibility of systemic reactions to prick-tests in highly sensitized people. Several studies published in the literature have used commercial extracts. As for airborne allergens, concentrations causing a skin reaction of 15 mm do not present a risk of systemic reactions. Prick-tests to native foods--prick-in-prick tests--have been less extensively studied. The CICBAA1 data, from 1,138 food allergic patients of all ages, cover 34,905 prick-in-prick tests to foods. The wheal of these prick-tests has been regulary registered. The risk of systemic reactions can be evaluated at 0.008 %. There were no severe reactions and anti-histamine and corticosteroid therapy were sufficient. These results are similar to those of the large study in 2000 carried out by Devenney in neonates (0.005%). A review of the literature reveals only a few severe reactions in adults. The authors draw attention to the necessary precautions: temporary contra-indication for skin prick-tests in children and adults with grade 3 or 4 asthma, with particular attention to such foods as all kinds of nuts, fish, etc.

Epidemiology of life-threatening and lethal anaphylaxis: a review

Severe anaphylaxis is a systemic reaction affecting two or more organs or systems and is due to the release of active mediators from mast cells and basophils. A four-grade classification routinely places 'severe' anaphylaxis in grades 3 and 4 (death could be graded as grade 5). Studies are underway to determine the prevalence of severe and lethal anaphylaxis in different populations and the relative frequencies of food, drug, latex and Hymenoptera anaphylaxis. These studies will also analyse the risk arising from the lack of preventive measures applied in schools (personalized management protocols) and from the insufficient use of self-injected adrenalin. Allergy-related conditions may account for 0.2-1% of emergency consultations. Severe anaphylaxis affects 1-3 per 10 000 people, but for the United States and Australia figures are even higher. It is estimated to cause death in 0.65-2% of patients, i.e. 1-3 per million people. An increased prevalence has been revealed by monitoring hospitalized populations by reference to the international classification of disease (ICD) codes. The relative frequency of aetiological factors of allergy (food, drugs, insects and latex) varies in different studies. Food, drug and Hymenoptera allergies are potentially lethal. The risk of food-mediated anaphylaxis can be assessed from the number of personalized management protocols in French schools: 0.065%. Another means of assessment may be the rate of adrenalin prescriptions. However, an overestimation of the anaphylaxis risk may result from this method (0.95% of Canadian children). Data from the literature leads to several possibilities. First, a definition of severe anaphylaxis should be agreed. Secondly, prospective, multicentre enquiries, using ICD codes, should be implemented. Moreover, the high number of anaphylaxis cases for which the aetiology is not identified, and the variation in aetiology in the published series, indicate that a closer cooperation between emergency specialists and allergists is essential.

Anaphylactic Reaction to Inulin: First Identification of Specific IgEs to an Inulin Protein Compound

BACKGROUND

A woman with a past history of allergy to artichoke presented with two episodes of immediate allergic reactions, one of which was a severe anaphylactic shock after eating two types of health foods containing inulin.

RESULTS

Dot blot assay techniques identified specific IgEs to artichoke, to yoghurt F, and to a heated BSA + inulin product. Dot blot inhibition techniques confirmed the anti-inulin specificity of specific IgE.

CONCLUSIONS

The absence of a positive reaction to an unheated milk-inulin mixture indicates the probability of protein-inulin binding. There is no cross-reactivity with the carbohydrates of the glycosylated allergens.