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Resume La synthese de proteines de defense fait partie des reponses biochimiques que les plantes ont developpees pour lutter contre leurs ennemis naturels et contre les stress environnementaux. De nombreuses proteines de defense vegetale sont allergisantes : chitinases, proteines de transfert lipidique LTP, proteines Bet v 1-like. Cet article rappelle les principales familles de proteines de defense vegetale, leur impact allergique et l'effet de certains procedes agricoles ou technoalimentaires sur l'allergenicite des aliments vegetaux.

Resume L'allergie au raison est rare : trois observations pediatriques sont connues et une vingtaine d'observations chez l'adulte. Les motifs de consultation sont, le plus souvent, un syndrome oral ; mais, des manifestations plus graves sont possibles : asthme, anaphylaxie a l'effort, choc anaphylactique. Les auteurs rapportent l'observation d'un garcon de 4 ans, presentant une allergie au raisin, dont les symptomes cliniques sont limites a un syndrome oral. Le diagnostic est affirme par les tests cutanes au raisin natif, le test labial et le dosage des IgE seriques specifiques. Cette allergie s'integre dans le cadre d'un syndrome d'allergies multiples : acariens, pollens de graminees, blanc d'œuf, poisson, noix de coco, kiwi, amande, latex. Les relations moleculaires, pouvant expliquer cette association d'allergies, sont discutees.

Resume Les explorations in vitro en allergie ont recours principalement aux dosages des IgE « specifiques » (IgE-S). Ces tests sont souvent denommes RASTs et leurs resultats exprimes a la fois en unites semi-quantitatives, les classes et en valeurs chiffrees, les kU l–1. Ce double systeme a-t-il obscurci la valeur et donc l’utilite clinique des resultats chiffres des tests in vitro ? Les dosages sanguins sont-ils en soi suffisants pour poser un diagnostic d’allergie ou pour predire une future allergie ? Les courbes de risque recemment proposees et fondees sur des etudes de populations peuvent-elles ameliorer l’efficacite des tests in vitro de ce point de vue ? Cet article analyse ces questions sur la base d’arguments theoriques et experimentaux. Il en ressort que les resultats chiffres des dosages d'IgE-S ne traduisent pas fidelement l'expression clinique du patient et ne doivent donc etre interpretes qu'avec le reste du dossier du patient. Les courbes de risque ne sont pas une meilleure solution car elles ajoutent a ces limitations des IgE-S un autre probleme : ces courbes sont fortement dependantes des caracteristiques des cohortes de sujets qui ont servi a les calculer (âge, environnement etc.). Aussi, l'interet de ces courbes pour un patient donne est tres limite en pratique quotidienne.

Resume Certains additifs, contenus dans des aliments ou des medicaments, peuvent etre a l’origine de reactions allergiques. Un nourrisson de 26 mois avait presente un eczema lie a une polyallergie a l'œuf, a l'arachide et aux acariens. Apres une periode d’amelioration, l’eczema s’aggrave, avec apparition d’une urticaire. Certaines de ces poussees surviennent apres consommation de sirop de mequitazine et de betterave cuite. L’intolerance au benzoate va etre confirmee par un test de provocation. L’evolution a ete favorable apres eviction de cet additif. La reintroduction apres trois ans et trois mois est possible, posant le probleme de la duree d’eviction.

En France, en 1992, l'industrie propose pour les nourrissons une variete considerable de laits infantiles: pas moins de 59 specialites. Malgre les limites de composition fixees par la reglementation sur les aliments lactes dietetiques pour nourrissons (ALDN), certains fabricants proposent plus de deux laits dans une meme categorie d'usage! Malgre tout, ces laits sont loin d'etre equivalents et l'ouverture du marche uique europeen risque de compliquer encore le choix du meilleur lait pour chaque enfant. Nous presentons une approche graphique des differences principales entre ces preparations, approche que nous pensons utile au choix rapide mais raisonne d'un lait.

Cross-reactive carbohydrate determinants (CCD) are well known interferants in specific IgE assays (sIgE). Glyco-epitopes are not restricted to CCD and extracts used to prepare in vitro tests contain many other glycoproteins able to bind glycan-specific IgE. The overall amounts of IgE-bindable glycan structures in allergen sources are unknown.We aimed at quantifying the influence of N-glycan structures on IgE reactivity to commonly tested allergen sources.IgE reactivity to 51 allergen extracts, one purified natural allergen and 10 recombinant allergens was measured on Phadia UniCAP system using 2 sera demonstrating significant levels of glycan-related IgE reactivity. Immobilized bromelain and horseradish peroxidase (HRP) were used to capture N-glycan-specific IgE from these sera. Residual IgE reactivity was measured for 42 allergen sources and 4 recombinant/purified allergens.An obviously excessive number of positive CAP-results were obtained with both sera, especially for plant-based allergen sources. Capture of glycan-specific IgE led to a decrease of serum IgE ractivity, variable among allergen sources and between sera. Among others, peanut results were proven largely interfered by the presence of glycan-specific IgE. Unexpectedly some allergen sources showed a slight influence of glycan-related reactivity, such as cockroach, mosquito, mussel, shrimp and domestic mites.In patients sensitized to pollens or to Hymenoptera venoms sIgE results should be interpreted with caution. One cannot substract the result of a glyco-reporter test (bromelain and/or HRP) in order to compute glycan-free slgE results for common allergen sources like peanuts. As long as the demonstration of a significant role for glycan structures in clinical allergic reactions is lacking, a simple pre-treatment able to discard glycan-specific IgE from serum would be useful to improve accuracy of in vitro diagnostic tests.

Introduction Un allergene est une molecule (Consensus 2013 WAO – ARIA – GA2LEN). Et c’est une molecule apte a engendrer une reaction allergique in vivo (WAO Nomenclature Committee 2004). Parmi les proteines IgE reactives connues en 2015, combien ont une allergenicite verifiee in vivo et sont donc des allergenes ? Cette question revet une grande importance car, pour que l’approche moleculaire du diagnostic soit pertinente, il faudrait n’y inclure que des proteines dont l’allergenicite in vivo a ete verifiee, c’est-a-dire des allergenes. Que vaudrait, en effet, un resultat positif pour une proteine dont la reactivite n’a ete etablie qu’in vitro ? Methodes La base de donnees Allergome ( http://www.allergome.org ) a ete analysee en se focalisant sur les proteines issues des produits naturels allergisants chez l’Homme. Pour chaque proteine le niveau maximum de reactivite a ete releve, selon une echelle allant des tests de laboratoire aux tests in vivo. Resultats Sur les 1662 proteines etudiees il apparait que seulement 17,6 % d’entre elles relevent de l’appellation d’« allergenes » pour avoir montre leur capacite a positiver un test cutane (15,6 %) ou un test de provocation (2 %). Les positivites pour un test d’activation des basophiles (5,8 %), un test serique « quantitatif » (Elisa, CAP… : 45 %) ou un test serique qualitatif (immunoblot : 31,6 %) montrent bien une IgE-reactivite mais ne peuvent affirmer que les proteines concernees sont aptes a provoquer une reponse clinique. Discussion Pour les patients, l’approche moleculaire du diagnostic represente une avancee majeure. Il convient cependant d’etre prudent dans l’interpretation des tests in vitro en distinguant bien les allergenes verifies des autres proteines IgE reactives qui ne sont, jusqu’a preuve du contraire, que des hypothetiques allergenes. Et ce serait le devoir de la communaute scientifique et des industriels d’aider l’allergologue en faisant un reel effort sur le plan semantique afin de distinguer clairement les « allergenes » et les « proteines IgE reactives » seulement.

Wheat is the staple cereal in many countries and its uses in manufactured foods are ever growing due to the technological qualities of gluten proteins. Transglutaminases (TG) are ubiquitous enzymes with many functions. They are able to transform proteins by deamidation and/or transamidation. This last reaction can cross-link proteins together. Intestinal tissue TG has been shown to play an important role in two kinds of immune reactions to wheat: celiac disease and wheat-dependent exercise-induced anaphylaxis. In addition, new epitopes have been suspected in cases of anaphylaxis to wheat isolates, a food ingredient consisting mainly of deamidated gluten proteins. As a microbial TG is included in many food technological processes, its safe use should be checked. This assessment must cover not only the safety of the TG itself but also that of the deamidated/cross-linked proteins generated by this enzyme. This article aims at discussing the possible consequences of using TG in food industry in the light of today knowledge about immune reactions to wheat.

Cross-reactive carbohydrate determinants (CCD) differ from classical peptide epitopes because their cross-reactivity is not restricted to a protein family or domain. They can be considered as panepitopes. Antigen presenting cells (APC) express membrane receptors for IgE. APC-bound IgE are able to widen the patient's sensitization spectrum through cross-binding of allergens belonging to the same protein family or domain. In the case of carbohydrate panepitopes the same mechanism could induce a much larger array of new sensitizations than peptide epitopes can do.

Recent progress in understanding structural relationships between allergens has allowed their classification into molecular families. Proteins belonging to a molecular family often show some degree of IgE cross-reactivity. These cross-reactions can lead to a clinical association like birch-apple syndrome whose basis is a sensitization to a PR-10 protein (birch pollen Bet v 1) and then oral symptoms in contact to apple Mal d 1, another PR-10 family member. Food allergens implicated into pollen-food allergy syndromes differ from those linked to crustacea or milk cross-allergies: they seem unable to sensitize the patient through oral route. As a result, they most often induce weaker clinical reactions than complete allergens like those present in shrimp or cow milk. Numerous molecular families have been isolated from pollens. PR-10 and profilins have a well established role in inducing clinical reactions to food like fruits and vegetables. Some molecular families need more studies to delineate their true impact on pollen-driven food reactions: polygalacturonases, pectate lyases, isoflavone reductases, thaumatin-like, cyclophilins.... Others are found in pollen but not in eaten products: 2-EF-hand calcium binding proteins, beta expansins,... Lipid transfer proteins (LTP) are widespread plant food allergens (e.g. in peach): these proteins seem able to directly sensitize the patient through oral route. But recent data have suggested a possible additional effect of some LTP present in pollens (mugwort, olive, pellitory).

As an alternative to gas chromatography, the enzymatic UV assay of ethylene glycol is often used by emergency laboratories. Many variants of this technique have been published, all based on the reaction between NAD(+) and ethylene glycol in the presence of glycerol dehydrogenase (EC 1.1.1.6). We show that other alpha-diols interfere in this reaction. Some of them, like 2,3-butanediol, give false positive reactions; whereas other diols, e.g. glycerol and propylene glycol, interfere only when ethylene glycol is present in the sample and lower the ethylene glycol response; these interferents are of particular concern because some parenteral drugs used in emergency situations contain glycerol or propylene glycol in their vehicle. This drawback has hitherto been largely underestimated, and we think that ethylene glycol results obtained with these enzymatic techniques should be interpreted with caution, even if the sample is pre-treated with glycerokinase (EC 2.7.1.30); this pre-treatment effectively corrects the glycerol interference but not that of propylene glycol.

A new CEDIA assay for the measurement of digoxin in serum on random access analyzers was evaluated by twelve laboratories in Europe and the United States. Studies on the analytical range, reproducibility, calibration stability, recovery in controls, interlaboratory comparability, comparability with routine methods, and the effect of various interfering factors have been performed and the results are presented in this paper. The analytical performance was comparable to that of routine methods provided the manual pipetting step for pre-incubation was performed with accurate pipettes. A major advantage of the CEDIA Digoxin assay in terms of convenience is the simple two-point calibration procedure. Moreover, digoxin can be determined within 15 minutes after receiving the samples on random access analyzers like Boehringer Mannheim/Hitachi analysis systems. Thus, the CEDIA Digoxin assay represents an attractive alternative to the measurement of digoxin on dedicated immunochemical assay systems.

We evaluated a CEDIA assay for the determination of digitoxin in serum on random access analyzers. The multicenter evaluation included studies on the analytical range, calibration stability and reproducibility of the new assay. Moreover, recovery in controls, transferability of results obtained in different laboratories, comparability with routine methods, and the effect of various interfering factors have been analyzed. Summarized the analytical performance was comparable to that of routine methods. The CEDIA Digitoxin assay represents an attractive alternative to established digitoxin immunoassays because it can be performed on random access analyzers, thus permitting the simultaneous determination of digitoxin and other serum analytes without sample splitting.