Mise au point d'un dosage automatisé des IgE spécifiques des allergènes des pollens de cyprès et de genévrier par VIDAS Stallergy

Study objective

Cypress pollen is a significant cause of allergies in the Mediterranean area. In order to improve the in vitro diagnosis to cypress sensitization, we used a Juniperus ashei extract to develop a new semi-quantitative test for the measurement of IgE specific to juniper and cypress pollen allergens based on the VIDAS automated system.

Methods

The VIDAS Stallergy^® assay combines a two-step enzyme immunoassay sandwich method with a final fluorescence detection. The reagent comprises the Solid Phase Receptacle (SPR) coated with a J. ashei extract, which serves as a solid phase as well as a pipetting device during the assay and a strip that contains all the ready-to-use reagents.

Results

The precision study shows coefficients of variation lower than 1.7% for intra-assay variability and between 1.6 and 9.5 for inter assays variability. Correlation with the CAP system^® method shows an 80.7% agreement to the nearest class (N = 57). For 65% of sera class results are similar with the two techniques, and for 33% of sera, class results are higher with the VIDAS method. Test specificity is confirmed by VIDAS inhibition experiments. A sensitivity study performed using 82 clinically recognized cypress allergic patients shows that 97.6% of the patients are detected with the VIDAS Stallergy^® Juniper reagent.

Conclusion

The Juniper Stallergy^® test allows to measure specific IgEs to cypress pollen, with a sensitivity of detection at least similar to the CAP system^® method.     

La marche de l'allergie : que reste-t-il de l'histoire dite naturelle de l'allergie ?

Until recently, it was generally agreed that the natural history of allergy overlapped with that of asthma. The dominant concept was that allergy, in particular, allergy to perennial aeroallergens, was the most important cause of asthma. The classical curves of the age-related incidence of the main allergic syndromes, i.e. those closely associated with asthma, made it appear that the first step in the natural history of atopy was atopic dermatitis, followed by asthma and rhinitis. Allergy to one or more foods, especially cow milk and egg, began early in life, very often disappeared, leaving place for the development of sensitivity to aeroallergens. This classic schema allowed one to suppose that primary prevention was possible and that by avoiding the main allergens very early in life one could reduce the subsequent risk of allergic sensitization and, therefore, of asthma as well. The interest in prevention was explained by the growing prevalence of allergic diseases, which had become an important public health problem. In fact, the natural history of asthma and allergy is much more complex, being a real puzzle in which one must take into account the allergens, life style (rural or urban), contact with animals, endotoxins, parasites, atmospheric pollution (e.g. the association between diesel particles and pollen), hygiene, infections and immunizations, breast feeding, pasteurized or non-pasteurized cow milk, the diet and many other factors. The aim of this critical review is to try to untangle this maze.     

Explorations non invasives des voies aériennes : applications pratiques dans l'asthme et l'allergie

Non-invasive investigation of airway inflammation relies mainly on measurement of exhaled gases (essentially NO) and several markers of inflammation in exhaled breath condensate (EBC). Levels of exhaled nitric oxide (NO) are easily and quickly measured. International recommendations for standardized measurements of exhaled NO have been published. Exhaled NO is increased in patients with untreated asthma; the results of this measurement may be useful when the diagnosis is difficult or when there is a chronic asthma-like cough. Exhaled NO is reduced or normalized with inhaled corticosteroid therapy. An increase in exhaled NO in an asthmatic whose condition has been well controlled may signal a clinical exacerbation. The place of exhaled NO measurement in the diagnosis and treatment of asthma should rapidly be publicised because of its simplicity and because of the availability of reliable devices for its measurement. Many inflammatory mediators can be measured in EBC obtained by rapid cooling of exhaled air on a cold surface. Although collection of EBC is non-invasive, at present lack of standardisation limits its application and interpretation in practice. In cases of asthma, the pH of EBC is lower than normal and the concentrations of leukotrienes, 8-isoprostane and H₂O₂ are higher. Levels of the mediators detected in EBC decrease rapidly in asthmatic patients treated with steroids but this treatment is less effective on oxidative stress markers. Exhaled NO and EBC are complementary in the non-invasive approach to the evaluation of airway inflammation in asthma and atopy.     

Allergie aux protéines du lait et aux hydrolysats de protéines de lait : à propos d'une observation au diagnostic retardé

The authors report the case of an infant with a history of eczema due to cow milk and who later had two bouts of urticaria after drinking milk protein hydrolysate. The particular interest in this case is the disconnection between the onset of the eczema (when an allergy workup was not predictive) and the subsequent finding, one year later, of positive IgE-dependant sensitization tests.