The importance of EN ISO 15189 accreditation of allergen-specific IgE determination for reliable in vitro allergy diagnosis.

BACKGROUND: Allergen-specific serum immunoglobulin E detection and quantification have become an important step in allergy diagnosis and follow-up. In line with the current trend of laboratory test accreditation to international standards, we set out to design and assess an accreditation procedure for allergen-specific serum IgE. METHODS: Method validation according to the accreditation procedure under the EN ISO 15189 standard was carried out for allergen-specific immunoglobulin E determination using the fluoroimmunoenzymatic method ImmunoCAP(®) (ThermoFisher). Data were produced by 25 hospital laboratories in France. A total of 29 allergen specificities including mixes, extracts, and molecular allergens were assayed. Allergen-specific serum immunoglobulin E concentrations ranged from 0.1 to 100 kUA /l. RESULTS: Repeatability, reproducibility, and accuracy results fulfilled method validation criteria for automated laboratory tests and proved similar irrespective of the allergen specificity, allergen-specific serum immunoglobulin E concentration, or individual laboratory. CONCLUSION: Allergen-specific serum immunoglobulin E determination with the fluoroimmunoenzymatic method ImmunoCAP(®) is a highly repeatable, reproducible, and accurate method which may be considered as a single analyte assay in view of the EN ISO 15189 accreditation procedure.

[Neonatal screening of glucose-6-phosphate dehydrogenase deficiency in umbilical cord blood]. / Dépistage néonatal du déficit en glucose-6-phosphate déshydrogénase (G6PD) sur sang de cordon.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most frequent enzyme deficiency. It is a sex-linked genetic disease concerning mostly african, mediterranean and far-eastern populations. The main clinical expression is a hemolytic anemia which can be acute or chronic. During the neonatal period the disease may manifest as neonatal jaundice. We have been asked by the neonate department to set up a blood screening test for this deficiency. We have therefore developed a test using umbilical cord blood. The assay of G6PD has been automatised and red blood cell aspartate-amino-transferase (ASAT) chosen as a reference enzyme to evaluate the age of red blood cells. Normal values of G6PD, ASAT and G6PD/ASAT ratio have been calculated from 235 cord samples. Genetic frequency of this deficiency in 2002 was 6% in male and 1% in female newborns.

[Are there milder forms of the syndrome called hyper-IgE? Diagnostic problems. Apropos of 2 cases]. / Existe-t-il des formes mineures du syndrome dit d'hyper IgE? Problèmes diagnostiques. A propos de deux observations.

We present the observations of two boys eight and four years old whose the only clinical sign is a chronic otorrhea. We found many of usual features of the hyper IgE syndrome: raised total IgE (4000 to 8000 Ul/ml) and hypereosinophilia (1100 to 3800/mm3). We found a lowered proportion of CD8+ cells (suppressive or cytotoxic): 16 and 18% (normal values: 26 +/- 5%). The chemotaxis of polymorphonuclears is also lowered: 9.2 to 6.0 cells by microscopic field with FMLP presence (normal values 40 to 50). These two observations are compared with other literature cases where clinical picture is moderate, but biological signs very suggestive.

[Long-term tolerance of specific hyposensitization with the aid of calcium phosphate-adsorbed mite extracts]. / Tolérance à long terme de l'hyposensibilisation spécifique à l'aide d'extraits d'acariens adsorbés sur phosphate de calcium. A propos de 90 observations traitées de façon semi-rapide.

90 children receive a specific hyposensitization with calcium phosphate adjuvant purified Dermatophagoides pteronyssinus allergens. We note 44% very good results, 37% good results and 19% failures. We propose to begin with 1/1,000,000 concentration every other day until 1/10,000 concentration is obtained under antihistamine protection. Tolerance is satisfactory: moderate respiratory reaction are pointed out for 22 patients. No anaphylactic shock is encountered. For 80 children with more than three years recall, we totalled 3,700 injections for 340 watching years. Only eight patients are sight lost. 1/10,000 concentration is obtained in 72/80 followed up children.

[Chronic rhinopathies of childhood (apropos of 265 cases)]. / Les rhinopathies chroniques de l'enfant (à propos de 265 observations).

We observed among 265 children with a chronic rhinopathy: 187 allergic rhinopathies, associating sneezing, rhinorrhea and nasal eosinophilia, particularly caused by a sensitization for mites. 10 non allergic eosinophilic rhinopathies with identical clinical signs, and major nasal eosinophilia without any allergic factor. 68 non allergic non eosinophilic rhinopathies, where are preponderant nasal obstruction, olfaction troubles, ORL infections (otitis and sinusitis). Their etiology is probably various: psychic factors, ciliary dyskinesias, vasomotor phenomena...

[Are the left-handed more often allergic?]. / Les gauchers sont-ils plus souvent des allergiques?

Are left handed more frequently allergic patients? With the same evaluation clinical criteria, we find a Non Right Handedness (left handed + mixed handedness) in 48/403 children (11.9%) at school in a town near our consultation place and in 152/625 (24.32%) children of the same age with a mites allergy (p less than 0.001). This non right handedness is among allergic patients more frequently observed for boys: 126/442 (28.50%) than for girls: 26/183 (14.20%). The mechanism is unknown but it has been hypothesized (Geschwind) that a male related factor might slow left hemisphere development and trouble immune system equilibration.

[Comparative study of 3 positive controls for routine prick tests in children: 48/80, 1 mg histamine and 5 mg histamine]. / Etude comparative chez l'enfant de trois témoins positifs pour la pratique des prick tests: 48/80, histamine 1 mg et histamine 5 mg.

We compared, among 153 children 2 to 14 years old, responses to some positive control solutions for prick tests made with a Stallerpoint. We obtained the following values: -6% - 48/80:4.46 +/- 1.88 mm -1 mg/ml Histamine:3.49 +/- 1.67 mm -5 mg/ml Histamine:5.13 +/- 1.78 mm. 1 mg/ml histamine gives too many null responses (12/153) to represent a valuable positive control. 5 mg/ml histamine, on the other hand, gives some very strong reactions which may induce an underestimation of responses to allergen tests. Compound 48/80 seems to remain the best positive control for prick test exploration of immediate allergy in children. An alternative might be an intermediate solution of histamine 2.5 mg/ml.

[Is it necessary to test children having summer respiratory problems with cereal pollens?]. / Faut-il tester aux pollens de céréales les enfants présentant des troubles repiratoires estivaux?

We tested 100 children with clinical signs that occurred in spring or summer. Prick tests were made with extracts of wild grass pollens (Dactylis, Phleum, Lolium) and with separate cereal pollens (Wheat, oats, Sweet-corn Barley and Rye). In 20 children whose test was negative for wild grass pollen, we saw no sensitization to cereals. In 80 children with grass pollenosis, Barley and Rye are the cereals that gave the most positive prick tests, whilst sweet corn is the cereal with most negative tests.

[Comparison of specific IgE levels versus various milk proteins in 76 eczematous children]. / Comparaison des dosages des IgE spécifiques vis-à-vis des diverses protéines du lait chez 76 enfants eczémateux.

Among 76 eczematous children, we realized a RAST test for whole milk and milk specific proteins: lactalbumin, lactoglobulin and casein. One of these RAST tests, at least, was positive for 27 children. Whole milk RAST test is the most frequently positive (77%) but some non specific reactions seem to interfere: only three children are clinically milk sensitive. Among specific proteins, lactalbumin is more frequently positive (59%) than lactoglobulin (51%) and casein (18%). Eczematous children with positive milk RAST tests, if compared to other eczematous children, have currently more mite allergies and positive egg RAST tests. They have a tendency (non significative) to be more frequently breast fed. The positivity of milk RAST tests seems to belong to a polysensitization and infrequently concerns a clinical allergy.

[Severe local reactions to mosquito bites. Apropos of 20 cases]. / Les réactions locales majeures aux piqûres de moustique. A propos de 21 observations.

We relate 21 observations of children who present major local reactions, immediate and delayed after mosquito bites. An associated reagin mechanism is obvious in 8 patients: five positive cutaneous or RAST tests and three a basophil degranulation tests. They are mostly young children (14/21 an less 5 years old). After some difficult years, the evolution is finally favourable with a specific hyposensitization or under antihistaminic protection (ketotifen) during summer.

[Does the allergic child become sensitized to small domestic mammals (guinea pig, hamster, rabbit?)]. / L'enfant allergique se sensibilise-t-il aux petits mammifères domestiques (cobaye, hamster, lapin)?

Our own works show among allergic children a frequency of sensitization of 30% to cats and of 17% to dogs. But, the proportion of sensitizations to other small domestic mammals such as guinea pigs, hamsters of rabbits seems to be unknown. Among atopic children with a known contact with those pets we noted: for guinea pig: 29% positive cutaneous or RAST tests 21% clinical signs in presence of animals; for hamster respectively 28% and 6.5%; for rabbit respectively 18% and 12.3%. Guinea pigs seem to be more sensitizing animals, followed by rabbits, then by hamsters. As for cats and dogs, eviction is imperative when a sensitization is demonstrated.

[What problems does childhood toxocariasis currently pose? Apropos of 6 clinical cases]. / Quels problèmes posent actuellement les toxocaroses de l'enfant? (a propos de six observations cliniques).

About six observations of toxocariasis (visceral larva migrans syndrome). We relate six observations of toxocariasis among children. In one case, an ocular localization is probable. For other five patients, they are inapparent forms. The allergologist pediatrician may be consulted because of a major hypereosinophilia (greater than 10,000/mm3) and an elevation of total IgE (greater than 2,000 UI/ml). Allergic and current parasitologic assays are negative and diagnostic key is given by toxocara serology. We insist on interest and reliability of passive hemagglutination test with a purified antigen (titer greater than or equal to 1/320). Treatment now is preferably flubendazole (50 mg/kg/day for six days) eventually renewed.

[Does immediate-type respiratory allergy occur regarding Stemphylium? Evaluation of 39 challenge tests]. / L'allergie respiratoire de type immédiat existe-t-elle vis-à-vis de Stemphylium? Bilan de 39 tests de provocation.

Does immediate respiratory allergy with stemphylium exist? About 39 provocation tests. We present 39 children with positive cutaneous and/or RAST tests for stemphylium mold. Provocation tests individualize 19 patients (14 boys and 4 girls, 10 to 16 years old in 17/19) with a respiratory sensitivity: 6/10 by passive anterior rhinomanometry and 13/15 by bronchial tests. Clinical symptoms are asthma and spasmodic rhinitis (14/19), predominantly from june to august. We noted a mite allergy in 11 cases and a grass pollenosis in 13 children. Positive cutaneous and/or RAST tests are found for alternaria mold in 13/19 cases. We undertook a specific hyposensitization in 14 children with a three years experience in 10 cases. Tolerance is excellent. This provocation respiratory exploration shows the important role played by stemphylium mold in the etiology of recurring respiratory incidents in children.

[Role of rhinomanometry in childhood mite allergy apropos of 76 cases]. / Place de la rhinomanométrie dans l'allergie aux acariens de l'enfant à propos de 76 explorations.

Place for Passive Anterior Rhinomanometry (PAR) in mite allergic children. PAR is a simple method to investigate chronic or recurrent rhinopathies in children. Among 59 investigations with a Dermatophagoides pteronyssinus extract, we found 27 positive responses, 3 doubtful results and 32 negative explorations. Nasal sensitization is usually important: the liminal dose is less than 250 mcg in 17/28 cases. Most children have no bronchial sensitivity. None of 14 children with negative cutaneous and RAST tests have nasal sensitivity. When cutaneous and RAST tests are both positive, 12/16 positive PAR are found. We note a nasal sensitivity in 3/5 cases with only cutaneous test positive and 12/26 cases with only RAST tests positive. For other mites a nasal sensitivity is found in 8 out of 14 explorations (Tyrophagus and Glyciphagus especially). Among all patients when cutaneous tests, RAST tests and history are doubtful for the real part played by mites in the child rhinopathy, nasal exploration allows more explicit diagnostic and therapy.

[Does mugwort pollenosis occur in children in the northern region?]. / La pollinose à l'armoise est-elle fréquente chez l'enfant dans la région nord?

Is Mugwort pollenosis frequent among children in North of France? In North of France where no ragweed grows, mugwort (artemisia) is after grasses and plantago, the third pollenosis in children. Among 184 children with summer clinical signs, positive cutaneous tests with a mugwort extract are noted in 40 patients (21%). RAST are positive only in 23 on 34 children with positive cutaneous test. Among the 40 children only two are less 5 years old and 26 are more 10 years old. Respiratory provocation tests confirm in 13/19 cases a sensitization of upper or lower respiratory tract. No food allergy exists among those children.

[Can Acarus siro be considered an allergenic mite in children? Evaluation of 248 cases]. / Acarus siro peut-il être considéré comme un acarien allergisant chez l'enfant? Bilan de 248 explorations.

Among 248 allergic children we noted 44 children (21%) with strongly or moderately positive cutaneous tests (In seven out of these tested children respiratory provocation tests are very positive). They are urban children and their houses are not different from other allergic children. They are mostly boys (72%), more than 5 years old (91%), with an asthma (84%), a radiological sinusitis (45%), an hypereosinophilia (88%) and elevated total IgE (90%). 43/44 children also have positive cutaneous tests to Dermatophagoides pteronyssinus mite. Since respiratory sensitivity is exquisite, we undertook a specific hyposensitization for some patients with encouraging results.