PubMed Health⌕ Search

Biomedical subjects

Thomas M Li

Publications and source records attributed to Thomas M Li.

3 recordsLinked to original sources
PubMed2005

Performance validation of a third-generation allergen-specific IgE assay in the clinical laboratory: interlaboratory and intermethod comparison.

BACKGROUND: Allergen-specific IgE (sIgE) measurements are used to help identify causative allergenic agents and to determine the degree of sensitization to facilitate treatment decisions. We examined the performance of a new third-generation chemiluminescent enzyme immunoassay for allergen-specific IgE (sIgE) on the continuous random access Immulite 2000 system. METHODS: Detection limit and dilutional linearity were determined. Within-run and total precision were assessed according to the NCCLS EP5 guideline. Interlaboratory comparison of the new Immulite 2000 third-generation allergen-specific IgE assay was performed, as well as intermethod comparison against the Pharmacia FEIA, a second-generation assay. RESULTS: The detection limit was <0.1 kU/l. Dilutional linearity held from 100 down to 0.2 kU/l. Regression analysis of the interlaboratory comparison results yielded: Immulite 2000(Laboratory 1)=1.07 Immulite 2000(Laboratory 2)+0.18 kU/l; r=0.98, n=3588 results. Intermethod comparison showed the following: Immulite 2000=0.83 (Pharmacia FEIA)+0.42 kU/l; r=0.79, n=512 results. Bland-Altman analysis of the interlaboratory and intermethod comparisons indicated no systematic bias. CONCLUSIONS: We confirmed the reported performance characteristics of the third-generation sIgE assay and found reasonably good interlaboratory and intermethod agreement. The extended range capability of the third-generation assay provides a new tool for investigating cutoffs and trends in childhood allergy disease progression at concentrations <0.35 kU/l.

Allergens↗
PubMed2004

Development and validation of a third generation allergen-specific IgE assay on the continuous random access IMMULITE 2000 analyzer.

In vitro determination of allergen-specific IgE (sIgE) represents an important aid in the diagnosis and treatment of allergy. Improvements in laboratory methodology--the development of second, and now third generation assays for sIgE--have brought about major advances in speed, convenience, performance, and in the standards for judging performance. In this study, following the NCCLS I/LA20-A guidelines, we evaluated the analytical performance of a quantitative chemiluminescent enzyme immunoassay for sIgE using the continuous random access IMMULITE 2000 system. Defining features of this "third generation" sIgE assay include a true zero calibrator with a detection limit and functional sensitivity of 0.1 and 0.2 kU/L, respectively. The use of liquid allergens allows for complete automation, fast binding kinetics between IgE and the natural allergenic protein conformations, and a time-to-first-result of 65 min. Stable reagents and the low nonspecific signal associated with the liquid allergens and centrifugal wash technique permit extension of the measuring range to 0.1-100 kU/L, based on lot-specific, factory-calibrated master curves standardized to the WHO 75/502 reference standard. The assay demonstrated good precision and linearity over its measuring range. Relative to a first generation RIA (mRAST, from Hycor), clinical sensitivity, specificity, and concordance were 88%, 92%, and 90%, respectively (n = 812). Quantitative comparisons to a second generation assay yielded a linear regression relationship of IMMULITE 2000 = 0.99 (Pharmacia FEIA) + 1.99 kU/L, r = 0.859 (n = 169).

Allergens↗