Background: High serum concentrations of monoclonal free light chain (FLC) kappa or lambda are markers of plasma cell dyscrasia. Methods: We developed new, latex-enhanced, specific nephelometric assays based on monoclonal antibodies for the determination of FLC kappa and lambda in serum, EDTA plasma and Li-heparin plasma for use on the Siemens BN systems. Results: Reference ranges were determined from 369 samples: FLC kappa 6.7-22.4 mg/L, FLC lambda 8.3-27.0 mg/L and kappa/lambda ratio 0.31-1.56. Protection from falsely low results due to antigen excess is obtained with a built-in pre-reaction in the assay protocols. Lot-to-lot consistency between three different lots of reagent, calibrators and supplementary reagent lots showed normalized differences -7.5%. The reproducibility of serum samples varied between 4% and 7%. The method comparison with Freelite assays showed normalized differences of 19.7%, 32.7% and 21.7%, respectively, for FLC kappa, lambda and ratio, correlations of 0.94, 0.77 and 0.73, and concordance rates of 99.2%, 94.2% and 95%. Conclusions: N Latex FLC demonstrates high precision, good lot-to-lot consistency and freedom from a high-dose hook effect. The method comparison between Freelite and the N Latex FLC assays showed good clinical concordance. Further studies need to reveal the clinical value of the new FLC assays.
Background: New monoclonal antibody-based assays for serum-free light chains (FLC) have become available. Methods: In a clinical study with 541 patients, the new N Latex FLC assays were compared with the Freelite ™ FLC assays and immunofi xation electrophoresis (IF). Results:Comparison of the different FLC kappa ( κ ) assays showed a slope of 0.99 with a deviation of 5.0 % , r s = 0.92, for FLC lambda ( λ ) a slope of 1.22, deviation 13.8 % , r s = 0.90 and for the κ / λ ratio a slope of 0.72, deviation -4.6 % , r s = 0.72. The concordance for the FLC κ assays was 91 % , for FLC λ 85 % and κ / λ ratio 95 % . The clinical sensitivity and specifi city of the κ / λ ratios in the study were comparable: 60 % and 99 % for the N Latex FLC assay and 61 % and 97 % for the Freelite ™ assay. In IF-FLC positive samples, the N Latex FLC κ / λ ratio scored 20/23 (87 % ) samples outside the reference range and Freelite ™ 21/23 (91 % ). For IF-FLC negative samples, N Latex FLC assay κ / λ ratio scored 338/350 (97 % ) within the reference range and Freelite ™ scored 332/350 (95 % ). Conclusions:The concordance scores and the clinical sensitivity and specifi city of the new N Latex FLC assays and Freelite ™ assays appeared comparable, but there are some differences in measurement of concentrations between the methods.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.