Anaphylaxie alimentaire sévère et léthale : cas rapportés en 2002 par les réseau d'allergovigilance

La prévalence de l’allergie alimentaire est de 3,24 % dans la population française. Des facteurs environnementaux doivent être pris en compte dans l’augmentation régulière de fréquence : médicaments, tabac, nouveaux aliments, nouveaux ingrédients et nouvelles technologies. Un système d’allergovigilance informant des risques nouveaux et de la fréquence des formes sévères d’anaphylaxie alimentaire est nécessaire. Le réseau d’allergovigilance, créé en 2001 comporte actuellement 250 allergologues français. Cent sept cas d’anaphylaxie sévère, dont deux mots, ont été rapportés en 2002 chez 33 enfants et 74 adultes. Les accidents cliniques enregistrés sont le choc anaphylactique : 59,8 % (un cas mortel à l’arachide), des réactions systémiques sérieuses : 18,7 %, un angi-œdème laryngé : 15,9 %, un asthme aigu grave : 5,6 % (un cas mortel au soja). Les allergènes les plus fréquents sont l’arachide (14), l’ensemble des noix (16), les crustacés (9), les fruits du groupe latex (9), la farine de lupin (7), la farine de blé (7), le céleri (5), les escargots (5). Une sous-estimation de la gravité, avec absence d’utilisation d’adrénaline est observée dans 59 % des cas. Plusieurs mesures d’intérêt public devraient être prises : communication des risques nouveaux aux industries agro-alimentaires, conseils d’amélioration d’étiquetage, directives de procédures de sécurité alimentaire pour les unités culinaires des hôpitaux. La création de tels réseaux dans d’autres pays européens pourrait contribuer à une avancée significative des connaissances quant aux particularités des allergies alimentaires liées aux habitudes alimentaires diverses. Les données de réseaux d’allergologues similaires au réseau national d’allergovigilance seraient un support important aux décisions autorités sanitaires françaises et européennes en matière de sécurité alimentaire.The prevalence of food allergy in the French population is estimated to be 3.24%. The constant increase in this prevalence is related to environmental factors: drugs, tobacco, new foods, new food ingredients and new food technology, all leading to increased allergenicity of ingredients. We decided that it was necessary to develop a system of food allergy vigilance to provide a continuous flow of information about the risk of allergy to new foods and data on the incidence of serious food-induced anaphylaxis. Therefore, a French Allergy Vigilance Network was set up in 2001; it now involves 250 French allergists. One hundred and seven cases of severe anaphylaxis (including two deaths) in 33 children and 74 adults were reported in 2002. Anaphylactic shock was reported in 59.8% of the cases involved (one fatal, to peanut); 18.7% were other systemic reactions, including 15.9% with laryngeal angioedema, 5.6% with serious acute asthma (one fatal, to soy). The most frequent allergens were peanut (14 cases), other nuts (16 cases), shellfish (nine cases), the latex-fruit group (nine cases), lupine flour (seven cases), wheat flour (seven cases), celery (five cases) and snails (five cases). The seriousness of these reactions was underestimated, as epinephrine was administered in only 59% of the cases. Several public interest measures should now be taken: communicate information about the new risk factors to the food industry, advise them to improve labelling, and encourage hospital catering services to set up guidelines for food safety. Setting up the same sort of network in other European countries could lead to a significant advance in knowledge with regard to the peculiarities of allergies relating to a wide variety of eating habits. Data that would be obtained by allergy networks similar to ours would be useful to French and other European health agencies responsible for making decisions concerning the safety of foods

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

How much does transgenesis affect wheat allergenicity? Assessment in two GM lines over-expressing endogenous genes

Wheat kernel albumins/globulins (A/G) and gluten proteins are responsible for baker's asthma and food allergy in atopic subjects. Although no commercial genetically modified wheats are currently being grown, they are under study and the allergenicity of GM products is a major concern.In order to establish the expected and unexpected effects of genetic transformation on allergenicity and also to carry out a safety assessment of genetic transformation, two GM wheat lines (bread and pasta wheat) transformed with endogenous genes were compared to their untransformed counterparts (wt), first by an allergenomic approach, and second, using ELISA with sera from patients suffering from food allergy to wheat and baker's asthma. The 2D immunoblots performed on sera from patients suffering from food allergy and baker's asthma on the A/G fraction of the four lines (two GM and two wt) revealed comparable IgE-binding profiles. A total of 109 IgE-binding spots were analyzed by mass spectrometry, and most of the proteins identified had already been described as allergens or potential allergens. Only two IgE-binding proteins were specific to one GM line. The concentration of specific IgE against the A/G fractions of GM wheat lines and their wt genotypes differed for some sera. Biological significance: The originality of our paper is to relate the transformation of wheat lines with their potential allergenicity using patient sera, such focus has never been done before in wheat and should be of interest to the researches working in this field.Another interesting point of this paper is the study of two types of allergies (respiratory and food) on two wheat genotypes and their GM which reveals that some allergens already known in respiratory allergy could be involved in children suffering from wheat food allergy.In this paper we used a classical 2D proteomic analysis and the protein identifications were performed by mass spectrometry after spot picking and in gel trypsin hydrolysis. Concerning the LC-MS/MS analyses classical software and parameters were used as described in Material and methods. We worked on wheat which is actually not fully sequenced that was a difficulty; we therefore searched against two databanks (proteins and ESTs) in order to compare the results. Moreover all proteins reported in our paper were identified with at least three unique peptides.The identified proteins were checked for their potential allergenicity. In order to have a best interpretation of protein identified in terms of potential allergens, BLAST alignments were performed by using an allergen databank (SDAP). This allows the determination of the cross-reactivity of these identified proteins with known allergens of other species and also the prediction of a potential allergenicity