ABSTRACT
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.
Subject(s)
Allergens/immunology , Fluoroimmunoassay/methods , Fluoroimmunoassay/standards , Hypersensitivity/diagnosis , Hypersensitivity/epidemiology , Immunoglobulin E/immunology , Humans , Hypersensitivity/immunology , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
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.
Subject(s)
Erythrocytes , Fetal Blood , Glucosephosphate Dehydrogenase Deficiency/diagnosis , Glucosephosphate Dehydrogenase/analysis , Neonatal Screening/methods , Acute Disease , Anemia, Hemolytic/genetics , Aspartate Aminotransferases/analysis , Chronic Disease , Erythrocyte Aging , Erythrocytes/chemistry , Erythrocytes/enzymology , Female , Fetal Blood/chemistry , Fetal Blood/enzymology , France/epidemiology , Gene Frequency , Genetic Variation/genetics , Glucosephosphate Dehydrogenase Deficiency/epidemiology , Glucosephosphate Dehydrogenase Deficiency/genetics , Glucosephosphate Dehydrogenase Deficiency/metabolism , Humans , Incidence , Infant, Newborn , Jaundice, Neonatal/genetics , Male , Neonatal Screening/standards , Prevalence , Reference Values , Sensitivity and Specificity , Sex DistributionABSTRACT
Injections of the 23-valent pneumococcal vaccine are usually well tolerated. Skin tests (prick and intradermal) and a self-made RAST with pneumococcal vaccine and phenol were performed in a child reporting a severe anaphylactic reaction induced by a 23-valent pneumococcal vaccine, and in ten control children, including one child with a well-tolerated vaccination, and nine non-vaccinated children. Skin tests and RAST with the vaccine were positive in the child reporting anaphylaxis, and negative in nine of the control children. Intradermal test with the vaccine was slightly positive in a non-vaccinated child with negative RAST. Skin tests and RAST with phenol were negative in all the children. These results suggest that immediate responses in skin tests and specific IgE determination have a good diagnostic value in children reporting severe reactions suggestive of IgE-dependent hypersensitivity to pneumococcal vaccine.
