[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).

Age-specific immunoglobulin g (IgG) and IgA to pneumococcal protein antigens in a population in coastal kenya.

Streptococcus pneumoniae is the primary etiological agent of community-acquired pneumonia and a major cause of meningitis and bacteremia. Three conserved pneumococcal proteins-pneumolysin, pneumococcal surface adhesin A (PsaA), and pneumococcal surface protein A (PspA)-are currently being investigated as vaccine candidates. Such protein-based vaccines, if proven effective, could provide a cheaper alternative to conjugate vaccine formulae. Few data from sub-Saharan Africa exist concerning the development of natural antibody to these antigens, however. To investigate the age-specific development of antiprotein immunoglobulin G (IgG) and IgA antibody responses, the sera of 220 persons 2 weeks to 84 years of age from coastal Kenya were assayed using enzyme-linked immunosorbent assays. IgG and IgA antibody responses to each antigen were observed in all age groups. Serum concentrations of IgG and IgA antibody responses to PspA and PdB (a recombinant toxoid derivative of pneumolysin), but not to PsaA, increased significantly with age (P < 0.001). No decline was observed in the sera of the elderly. Anti-protein IgG concentrations were only weakly correlated (0.30 < r < 0.56; P < 0.0001), as were IgA concentrations (0.24 < r < 0.54; P < 0.0001).