Les allergènes recombinants : leur apport à l’allergologie en 2006

Advances in molecular biology techniques have led to the production of recombinant allergens, about thirty of them now being available for measurements (DIAGNOSIS?) in vitro. These recombinant allergens correspond to a precise molecular variant of a natural allergen, and their biological activity has to be evaluated in comparison with the corresponding natural allergen. The advantages of recombinant allergens are essentially the creation of allergenic preparations having constant pharmaceutic properties, which allows determination of specific IgE directed against different molecular components of an allergenic source, for example, pollen, mites, etc. The main consequences of these biological advances are the following: evaluation of sensitivities to allergen molecules in different populations (molecular epidemiology), improvement of extracts used for diagnosis by selection of the most pertinent allergenic sources and in quantifying their major allergen content, definition of the spectrum of recognition of specific IgE vis-à-vis different molecular components (spectrotype), quantitative evaluation of IgE responses, establishing the molecular basis of cross-reactions between different inhaled allergens, between different food allergens, and between inhaled allergens and food allergens. As regards allergy practice, this new diagnostic tool can lead to better interpretation of polysensitivities, observed by skin tests and in vitro tests. Some examples of particular clinical cases associated with specific sensitivities vis-à-vis certain recombinant allergens will be presented.     

Allergie à la farine de blé chez l’adulte

The clinical manifestations of allergy to wheat flour are similar to those of allergies to other foods. In adults, food-dependent exercise-induced anaphylaxis, chronic urticaria, and gastrointestinal food allergies (that is, irritable bowel syndrome, eosinophilic colitis, ulcerative colitis) are the most frequently described clinical manifestations of allergy to wheat. Wheat isolates, used as binders and emulsifiers in the food industry, are neo-allergens resulting from chemically induced desamidation of wheat gluten (heating at high temperature in an acidic medium). Wheat isolate allergens can induce severe systemic reactions (e.g., urticaria) and anaphylactic shock. Diagnosis consists of three steps: a suspicion based on the patient's history, identification of the allergen by skin testing and by laboratory tests, and confirmation by oral challenge or by an avoidance regime.     

Intérêt des allergènes recombinants dans le diagnostic de l’allergie alimentaire

To date, neither in vitro nor in vivo tests can establish with reliability the diagnosis of food allergy. The availability of recombinant allergens (RA) has led to improvement in the standardization of allergenic extracts and enrichment of natural extracts, resulting in more sensitive screening tests. These biotechnological advances facilitate the diagnostic approach which now rests on an individual reaction profile (component resolved diagnosis) with well-characterized allergens classified on a molecular basis. Development of diagnostic tests using RA or peptides expressing some distinctive epitopes of interest may improve the prediction of severe and/or persistent food allergies and guide the choice of the therapeutic measures that follow.     

Mesure des allergènes de pollens d’arbre dans l’air (bouleau, olivier)

The information provided by pollen counts cannot be ignored by allergists and allergic individuals, but the divergence sometimes observed with clinical observations has led the réseau national de la surveillance aérobiologique (RNSA) to initiate the monitoring network of allergens by immunosampling (Monalisa) project. Moreover, some recent papers has shown the influence of pollution in the region and even of the year on the content in pollen allergens, particularly that of birch pollen. Thus, the goal of the Monalisa project was to set up a measuring system based on an immunological method that would result in validation of this new way of measuring airborne pollen counts. This European Life Environment project includes nine partners: Bertin Technologies (France), RNSA (France), NPARU (England), UCO (Spain), UTU (Finland), UAM (Poland), UEVORA (Portugal), AIA (Italy), and Meteoswiss (Switzerland). The results obtained during the 2006 season and then in the 2007 campaign, after modifications made in the sampler, were not very good. The principal results concern the measurement of birch and olive allergens, captured essentially in the prepollination period and sometimes in the postpollination period. Detection of these allergens may be due either to their presence on submicroscopic particles emitted independently of pollination, these allergens cross-reacting with birch and olive allergens. The difficulties encountered in this study lead us to say that pollen counts, phenological observations and clinical data are still the best way to assess the effects of airborne pollen.     

Les allergènes de la coiffure

Occupational dermatoses (or not) among hairdressers are very frequent. Intense exposure of hairdressers’ skin to water and to numerous chemical products may gradually damage their skin (as well as that of their clients). The hairdressers’ skin, and that of their clients, is exposed to many allergens all along the hairstyling procedures. The major sensitisers are para-phenylenediamine, thioglycolates, ammonium persulphate, nickel, thiuram compounds, fragrances, and preservatives.     

Œsophagite à éosinophiles : une cause rare de dysphagie

Eosinophilic esophagitis is an unrecognized and emerging entity. Its incidence increases with allergic disorders. A 29-year-old man presented with a 4-year history of intermittent and paroxysmal dysphagia. The triad including allergy, young age, and impaction of foreign bodies, combined with a chronic dysphagia is almost pathognomonic of eosinophilic esophagitis. Endoscopic esophageal features can be diverse, so systematic esophageal biopsies are required. Diagnosis is established with the demonstration of an eosinophilic infiltrate with a cell count exceeding 15 eosinophils per high power field (×400). First line therapy includes swallowed topical corticosteroids and removal of an allergic cause, when it could be identified.     

Les recombinants des panallergènes polliniques : application à l’interprétation des polysensibilisations

Multiple pollen sensitization is frequently encountered in patients who present with seasonal allergic respiratory symptoms. This regularly leads the allergist to question the significance of skin and laboratory test results because such results make it difficult to differentiate between cross-reactions and co-sensitization. Assays for specific IgE with recombinant panallergens, such as those in the profilin or polcalcin families, the results of which are now available in clinical practice, may lead to a better interpretation of such cases.     

Épidémiologie de l’allergie alimentaire

The epidemiology of food allergy normally relies on surveys using questionnaire in general populations and studies on cohorts and through professionals in allergy clinics, sometimes completed by prick-tests, specific IgE assays and/or oral challenges. Complementary data are supplied by specialized medical networks. In European countries, the prevalence of food allergy in the pediatric population is about 4.7%, and in adults it is about 3.2%. Striking disparities characterize the response to questionnaires in EU countries. Life-threatening anaphylaxis occurs in 1/10,000 inhabitants, fatal anaphylaxis in 1/1 million inhabitants. A drastic increase of life-threatening and lethal anaphylaxis has been noted in the UK and Australia over the past ten years. In France, there has been an increase of 28% between 2001 and 2006. The Allergy Vigilance Network, which includes 400 allergists, reports that this increase has occurred in the pediatric population. The prevalence of food allergies depends on age and consuming habits. Milk, egg, peanut and tree-nuts are at the top of the list in children. Prunoïdeae, latex-group fruits, Apiaceae, wheat and tree-nuts are the most important food allergens in adults. Peanut and tree nuts are the main offending allergens in severe anaphylactic cases. Since 2002 the Allergy Vigilance Network in France and Belgium has been identifying newly-appearing dangerous allergens. Molluscs, lupine flour and cashew nuts are the most common on this list and labelling these foods is now compulsory. Goat and sheep milk proteins (14 cases), buckwheat (25 cases) and wheat isolates are not yet required to be labelled. The danger of anaphylaxis to goat and sheep proteins (two deaths out of 14 cases) is due to the likelihood of their being masked allergens, for which reason the EU Scientific Agency should be made aware of the necessity of required labelling of foods containing these substances.     

Les allergènes croisants à l'échelle moléculaire : comparaison nord-sud

Fruit of the Rosaceae family, in particular apples and peachs, are frequent causes of food allergy. The clinical manifestations of these allergies differ as a function of geographic location. In the context of the SAFE project (QLK1-CT-2000-01394), financed by the European Community, the apple has been chosen as a model for the study of the relationship between the clinical presentation and the profile of sensitivity to Rosaceae allergens. This study included 389 patients allergic to apples and who live in four European regions: the Netherlands (Utrecht), Austria (Vienna), northern Italy (Milan) and central Spain (Madrid). Two different profiles of apple allergy were found in Europe: one in the Netherlands, Austria and in most of the patients (90%) in northern Italy, the other in Spain and in a minority (10%) of the Italians patients. Patients coming from regions where birch pollen is present become allergic to this pollen and to its major allergen Bet v 1 through contact via the respiratory tract; allergy to apple begins later as a consequence of cross-reactivity between Bet v 1 and Mal d 1. In Spain, allergy to apple is a result of primary sensitization to peach and its major allergen Pru p 3, subsequent allergy to apple being the consequence of cross-reactivity between lipid transfer proteins Pru p 3 and Mal d 3.     

Aortite et complications aortiques de l’artérite à cellules géantes (maladie de Horton)

Aortitis is a serious complication of giant cell arteritis (GCA), because of the risk of aortic aneurism, rupture, or dissection. Aortitis is present either at presentation or, more frequently, occurs as a delayed complication, typically as an aortic aneurism of the ascending part of the aorta. An aortic aneurism may occur in up to 10% of patients. Aortitis is sometimes associated to arteritis of the supra-aortic vessels. Risk factors for aortitis remain unknown. Recent clinical studies indicate that prevalence of aortitis was initially under-estimated. Imaging studies show signs of infra-clinical aortitis in 20 to 65% of cases at diagnosis. Using ultrasonography, thickening of the vascular wall with an hypoechoic halo around the abdominal aorta is suggestive of abdominal aortitis. Positron emission tomography shows a metabolic hypersignal of the aorta in about 50% of patients with giant cell arteritis. Aortic computed tomographic (CT) scan visualizes aneurysmal dilatations, ectasia or focal or concentric parietal thickenings. When present at the time of diagnosis of GCA, these findings seem to be associated with frequent relapses and perhaps with a higher long-term vascular mortality rate. Therefore, we recommend the screening of aortitis lesions at GCA diagnosis by an aortic CT-scan and follow-up. Therapeutic trials should be conducted to try to improve the treatment of aortitis in GCA.     

Éducation de l’allergie alimentaire sévère

Families consisting of children with food allergies have significant deficiencies in their knowledge of how to avoid allergen exposure and how to manage allergic reactions. Although an educational program can considerably improve a family's ability to manage allergic reactions to food and reduce the number of reactions, this approach is used too infrequently, even for children who have severe food allergies. A precise diagnosis is essential before undertaking such a program. It can result in reduction of the number of foods to be avoided and improvement in the child's quality of life. We will propose educational objectives for patients with severe food allergies and means to attain these objectives.     

Maladie de Dupuytren : l’aponévrotomie percutanée à l’aiguille est une alternative à la chirurgie

Dupuytren's contracture is a retractile fibrosis of the superficial palmar aponeurosis of the hand, resulting in a progressive and fixed flexion of the fingers that may result in severe limitation of hand function. It affects several millions of people in Europe and North America. Risk factors are genetic and sometimes related to mellitus diabetes. There is no spontaneous remission. Until recently, surgery was the only treatment, but now needle aponeurotomy emerges as a therapeutic alternative. It should be performed as first line treatment by a trained practitioner. Short and long-term results of needle aponeurotomy appear identical to those of surgery, with milder complications. It is indicated in palmar, palmo-digital, as well as in strictly digital forms of the disorder. The “table-test” is used to assess the loss of extension of the digit and to select the indication to needle aponeurotomy. A medico-surgical consensus should define the optimum treatment strategy in this affection.     

Caractéristiques clinicobiologiques des méningites à Enterovirus de l’adulte : étude de 59 cas

Purpose

To describe the epidemiological and clinical features of enteroviral meningitis as well as the biological profile of the cerebrospinal fluid (CSF).

Methods

A retrospective study conducted in a single centre between 2004 and 2008. All aseptic meningitis due to Enterovirus were included.

Results

Fifty-nine patients were included. The triad including fever, headache and neck stiffness was reported in 62% of patients. Twelve patients (20%) had a neutrophilic leukocytosis and 23 (39%) an elevated CRP level. Twenty-eight patients (47%) had a prominent neutrophilic reaction in the CSF and nine (15.2%) had a low glucose concentration. A presumptive anti-bacterial treatment was initiated in 47 patients (80%) for an average of 3.2 days.

Conclusion

Due to the lack of specificity of clinical features and biological manifestations of Enterovirus meningitis, the widespread use of real-time Enterovirus PCR is a priority for reducing the number of unnecessary anti-bacterial treatment. Guidelines based on clinical and biological features may be associated to help physicians in the differential diagnosis between bacterial and viral meningitides.     

Complications de la gastroentérite à éosinophiles : une observation et revue de la littérature

Introduction

Eosinophilic gastroenteritis is an unusual disease characterized by an eosinophilic infiltration of the gastrointestinal tract. The esophageal location of this disorder is uncommon and is usually revealed by dysphagia. Diagnosis is obtained by histology during endoscopy after exclusion of differential diagnosis. Treatment is based on systemic corticosteroids, which improve dramatically symptoms and endoscopic lesions.

Case report

We report an 88-year-old man who presented eosinophilic gastroenteritis with esophageal injury complicated by gastrointestinal haemorrhage and fistule.

Conclusion

Eosinophilic gastroenteritis may have a potentially unfavourable outcome. The treatment of complicated forms is not codified and often empirical.