[Performance criteria for the verification of IgE and tryptase assay methods: recommendations from the AllergoBioNet network]. / Critères de performance pour la vérification des méthodes de dosages des IgE et de la tryptase : recommandations du réseau AllergoBioNet.

Accreditation of an in vitro diagnostic assay according to the NF/EN/ISO 15189 standard requires to analyze its technical performance before implementation for routine use, and annually when reviewing effectiveness of quality controls. Performance is evaluated through repeatability, intermediate fidelity, accuracy and uncertainty of measurement. The coefficients of variation (CV) of the intra-assay and inter-assay precision tests must be compared with those of "peers" (results from laboratories employing the same method) and also with those obtained with "all methods", i.e., results from all laboratories performing the same assay, irrespective of the method. To our best knowledge, there is currently no French or international recommendation on what the acceptable limits of performance for specific IgE and tryptase assays should be. Therefore, the AllergoBioNet network of hospital allergy laboratories set out to characterize the performance of their current methods as a basis for the development of recommendations. The results provided by 24 centers were analyzed and led to consensus recommendations for specific IgE, total IgE and tryptase assays.

Pru p 7 sensitization is a predominant cause of severe, cypress pollen-associated peach allergy.

BACKGROUND: Peach is a common elicitor of food allergic reactions. Peach-induced immediate reactions may occur as benign pollen-food syndromes, usually due to birch pollen-related PR-10 cross-reactivity in temperate climates, and as potentially severe primary food allergies, predominantly related to nsLTP Pru p 3 in Mediterranean regions. The newly described peach allergen Pru p 7 has gained recent attention as a potential peach allergy severity marker. Sensitization to Pru p 7 and its allergenic homologues of the gibberellin-regulated protein family occurs in areas with high Cupressaceae tree pollen exposure. OBJECTIVE: We sought to investigate the distribution, clinical characteristics and molecular associations of Pru p 7 sensitization among subjects with suspected peach allergy in different regions of France. METHODS: Subjects with suspected peach allergy (n = 316) were included. Diagnostic work-up was performed according to current guidelines, including open food challenge when required. IgE antibody measurements and competition experiments were performed using the ImmunoCAP assay platform. RESULTS: Sensitization to Pru p 7 was present in 171 (54%) of all subjects in the study and in 123 of 198 (62%) diagnosed as peach allergic, more than half of whom were sensitized to no other peach allergen. Frequency and magnitude of Pru p 7 sensitization were associated with the presence of peach allergy, the clinical severity of peach-induced allergic reactions and the level of cypress pollen exposure. Cypress pollen extract completely outcompeted IgE binding to Pru p 7. Pru p 7 was extremely potent in basophil activation tests. CONCLUSION AND CLINICAL RELEVANCE: A subtype of Cupressaceae pollinosis, characterized by Pru p 7 sensitization, can be an underlying cause of severe peach allergy.

Diagnostic biologique des angioedèmes bradykiniques : les recommandations du CREAK.

Bradykinin mediated angioedema (BK-AE) can be associated either with C1Inhibitor deficiency (hereditary and acquired forms), either with normal C1Inh (hereditary form and drug induced AE as angiotensin converting enzyme inhibitors…). In case of high clinical suspicion of BK-AE, C1Inh exploration must be done at first: C1Inh function and antigenemy as well as C4 concentration. C1Inh deficiency is significant if the tests are below 50 % of the normal values and controlled a second time. In case of C1Inh deficiency, you have to identify hereditary from acquired forms. C1q and anti-C1Inh antibody tests are useful for acquired BK-AE. SERPING1 gene screening must be done if a hereditary angioedema is suspected, even if there is no family context (de novo mutation 15 %). If a hereditary BK-AE with normal C1Inh is suspected, F12 and PLG gene screening is suitable.

[For an efficient and reasonable accreditation of allergen specific IgE]. / Pour une accréditation efficace et raisonnable du dosage des IgE spécifiques d'allergènes.

French medical laboratories must be accredited before November 2016 according to NF/EN/ISO 15189 standard. However, technical accreditation guidelines cannot be applied literally for the determination of specific IgE for several reasons: more than 600 allergen tests, lack of international gold standard, limited external quality controls. Furthermore, the technique for determination of specific IgE is CE DM-IVD marked, common to all specificities, automatised, standardized according to a single calibration curve. Thus, we propose an efficient but reasonable solution conform to the idea of the accreditation by validating the process. We recommend: a flexible extend type A; choice of only one representative allergen (Dermatophagoides pteronyssinus) for repeatability and precision (20 tests, 2 levels 0.5-1 and 8-12 kUA/L) performed on patients sera, reproducibility (30 consecutive determinations using an Internal Quality Control/IQC), accuracy (IQC and rare External Quality Controls) compared with peers. Sensitivity, specificity, dynamic range, detection threshold are determinated by the provider. Linearity may be checked if the laboratory practices sample dilution for values higher than the upper limit guaranteed by the provider. In the absence of international gold standard, the uncertainty is not measurable. In case of change of instrument, the results obtained by the systems must be compared through 35 tests of different specificities distributed across the range of calibration and including 5 values close to the detection limit. This methodology allows a scientifically effective verification, technically and financially reasonable, to ensure the excellence of the performance of the laboratory with regard to peers and users (allergologists and patients).

Inherited deficiency of membrane cofactor protein expression and varying manifestations of recurrent atypical hemolytic uremic syndrome in a sibling pair.

Atypical hemolytic uremic syndrome (aHUS) is a rare thrombotic microangiopathic disorder that may be familial or sporadic. Complement factor H (CFH), factor I, and membrane cofactor protein (MCP; CD46), 3 regulators of the alternative pathway of the complement system activation, have been implicated in this pathological state. To date, 29 different mutations of CD46 have been reported, with incomplete penetrance and better clinical outcome compared with CFH mutations. Of those mutations, only 6 were found to be homozygous (accounting for 8 patients), and 5 resulted in a lack of or dramatically decreased cell-surface CD46 expression. We report here the seventh patient with a null mutation associated with recurrent aHUS. This mutation, a guanine to cytosine substitution in the first nucleotide of intron 2, disrupts a splice donor site. Interestingly, the patient's disease-free sister showed the same homozygous mutation. Extensive analysis of other complement regulatory protein- and polymorphism-associated risk factors did not uncover a difference between the patient and his sister. In conclusion, we describe for the first time a disease-free individual with complete CD46 deficiency, confirming the extremely variable penetrance and genetic complexity of aHUS.

Comparison of ADVIA Centaur and Pharmacia UniCAP tests in the diagnosis of food allergy in children with atopic dermatitis.

In a study comprising 63 children diagnosed with atopic dermatitis, the results of the ADVIA Centaur system was compared with the results obtained with the Pharmacia UniCAP100 system, which has been widely considered as a reference method for seric specific IgE (sIgE) measurements. The individual immunization against the most common food allergens [egg (f1), cow milk (f2), cod (f3), wheat (f4), peanut (f13) and soy bean (f14)] was determined by in vitro serum IgE testing and skin prick test (SPT). The comparison of the sIgE titers revealed a good concordance between the Centaur and the UniCAP tests for f1, f3, and f13 (94 %, 91 %, and 96 % respectively). However, the concordance was lower for f2, f4, and f14 (76 %, 77 %, and 77 % respectively) because of discrepancies between the two techniques. When compared with SPT and clinical diagnosis, on the 40 discordant cases found between the Centaur and the UniCAP, the Centaur showed concordance with the patients food reaction and SPT in 34/40 cases, and UniCAP in only 6/40 cases. Accordingly, the Centaur test displayed a statistically significantly better performance on specificity and concordance with SPT for f2, f4, and f14 (concordance/specificity = 70%/71%, 76%/75% and 90%/88% respectively), than the CAP test (49%/54%, 51%/52% and 67%/65% respectively).

Decrease in circulating dendritic cells predicts fatal outcome in septic shock.

OBJECTIVE: Biomarkers allowing accurate early staging of septic shock patients are lacking despite their obvious interest for patient management. Experimental models of septic shock in mouse previously noted a decrease in dendritic cell numbers. The aim of the study was to find a rapid reproducible biological test for an assessment of disease severity. DESIGN: Evaluation of peripheral blood dendritic cell counts by flow cytometry using three commercially available kits. PATIENTS AND PARTICIPANTS: Forty-two consecutive septic shock patients were studied prospectively. MEASUREMENTS AND RESULTS: Early low dendritic cell counts were correlated to disease severity as assessed by Simplified Acute Physiology Score or Sequential Organ Failure Assessment and predicted fatal outcome. The correlation was still present when the results were adjusted for age. CONCLUSION: The monitoring of blood dendritic cell count may provide an early and valuable assessment of the severity of the host response against infection and may influence the therapeutic management of septic shock patients.

Impact of safety devices for preventing percutaneous injuries related to phlebotomy procedures in health care workers.

BACKGROUND: Use of protective devices has become a common intervention to decrease sharps injuries in the hospitals; however few studies have examined the results of implementation of the different protective devices available. OBJECTIVE: To determine the effectiveness of 2 protective devices in preventing needlestick injuries to health care workers. METHODS: Sharps injury data were collected over a 7-year period (1993-1999) in a 3600-bed tertiary care university hospital in France. Pre- and postinterventional rates were compared after the implementation of 2 safety devices for preventing percutaneous injuries (PIs) related to phlebotomy procedures. RESULTS: From 1993 to 1999, an overall decrease in the needlestick-related injuries was noted. Since 1996, the incidence of phlebotomy-related PIs has significantly decreased. Phlebotomy procedures accounted for 19.4% of all percutaneous injuries in the preintervention period and 12% in the postintervention period (RR, O.62; 95% CI, 0.51-0.72; P < .001). Needlestick-related injuries incidence rate decreased significantly after the implementation of the 2 safety devices, representing a 48% decline in incidence rate overall. CONCLUSIONS: The implementation of these safety devices apparently contributed to a significant decrease in the percutaneous injuries related to phlebotomy procedures, but they constitute only part of a strategy that includes education of health care workers and collection of appropriate data that allow analysis of residuals percutaneous injuries.