title: N Latex FLC - new monoclonal high-performance assays for the determination of free light chain kappa and lambda.
abstract: 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.
authors.affiliation: Sanquin Reagents, Sanquin Blood Supply, Amsterdam, The Netherlands.
authors.forename: Henk Te
authors.initials: HT
authors.lastname: Velthuis
authors.affiliation: Sanquin Reagents, Sanquin Blood Supply, Amsterdam, The Netherlands.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Knop
authors.affiliation: Sanquin Reagents, Sanquin Blood Supply, Amsterdam, The Netherlands.
authors.forename: Peter
authors.initials: P
authors.lastname: Stam
authors.affiliation: Sanquin Reagents, Sanquin Blood Supply, Amsterdam, The Netherlands.
authors.forename: Monic
authors.initials: M
authors.lastname: van den Broek
authors.affiliation: Department of Immunopathology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Hannie Klaasse
authors.initials: HK
authors.lastname: Bos
authors.affiliation: Sanquin Reagents, Sanquin Blood Supply, Amsterdam, The Netherlands.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Hol
authors.affiliation: Sanquin Reagents, Sanquin Blood Supply, Amsterdam, The Netherlands.
authors.forename: Elisa
authors.initials: E
authors.lastname: Teunissen
authors.affiliation: Sanquin Reagents, Sanquin Blood Supply, Amsterdam, The Netherlands.
authors.forename: Karin Schulte
authors.initials: KS
authors.lastname: Fischedick
authors.affiliation: Department of Plasma Proteins, Siemens Healthcare Diagnostics, Marburg, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Althaus
authors.affiliation: Department of Plasma Proteins, Siemens Healthcare Diagnostics, Marburg, Germany.
authors.forename: Brigitta
authors.initials: B
authors.lastname: Schmidt
authors.affiliation: Department of Plasma Proteins, Siemens Healthcare Diagnostics, Marburg, Germany.
authors.forename: Carola
authors.initials: C
authors.lastname: Wagner
authors.affiliation: Sanquin Reagents, Sanquin Blood Supply, Amsterdam, The Netherlands.
authors.forename: Roel
authors.initials: R
authors.lastname: Melsert
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D006801:Humans; D007118:Immunoassay / Q000379:methods; D007145:Immunoglobulin kappa-Chains / Q000097:blood; D007146:Immunoglobulin lambda-Chains / Q000097:blood; D009391:Nephelometry and Turbidimetry / Q000379:methods*; D010265:Paraproteinemias / Q000175:diagnosis; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity
chemical_list: D000911:Antibodies, Monoclonal; D007145:Immunoglobulin kappa-Chains; D007146:Immunoglobulin lambda-Chains; D011933:Reagent Kits, Diagnostic