title: Clinical comparison of new monoclonal antibody-based nephelometric assays for free light chain kappa and lambda to polyclonal antibody-based assays and immunofixation electrophoresis.
abstract: 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 immunofixation electrophoresis (IF).
  
  
  RESULTS
  Comparison of the different FLC kappa (κ) assays showed a slope of 0.99 with a deviation of 5.0%, rs=0.92, for FLC lambda (λ) a slope of 1.22, deviation 13.8%, rs=0.90 and for the κ/λ ratio a slope of 0.72, deviation -4.6%, rs=0.72. The concordance for the FLC κ assays was 91%, for FLC λ 85% and κ/λ ratio 95%. The clinical sensitivity and specificity 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 specificity of the new N Latex FLC assays and Freelite assays appeared comparable, but there are some differences in measurement of concentrations between the methods.
authors.affiliation: Laboratory of Clinical Chemistry and Haematology, Jeroen Bosch Hospital, Den Bosch, The Netherlands.
authors.forename: Rein M J
authors.initials: RM
authors.lastname: Hoedemakers
authors.forename: Johannes F M
authors.initials: JF
authors.lastname: Pruijt
authors.forename: Suzanne
authors.initials: S
authors.lastname: Hol
authors.forename: Elisa
authors.initials: E
authors.lastname: Teunissen
authors.forename: Henk
authors.initials: H
authors.lastname: Martens
authors.forename: Peter
authors.initials: P
authors.lastname: Stam
authors.forename: Roel
authors.initials: R
authors.lastname: Melsert
authors.forename: Henk
authors.initials: H
authors.lastname: Te Velthuis
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D004586:Electrophoresis; D006761:Hospitals; D006801:Humans; D007145:Immunoglobulin kappa-Chains / Q000097:blood* / Q000276:immunology / Q000302:isolation & purification; D007146:Immunoglobulin lambda-Chains / Q000097:blood* / Q000276:immunology / Q000302:isolation & purification; D009391:Nephelometry and Turbidimetry / Q000379:methods*; D010265:Paraproteinemias / Q000097:blood; D012680:Sensitivity and Specificity; D012698:Serologic Tests / Q000379:methods*
chemical_list: D000911:Antibodies, Monoclonal; D007145:Immunoglobulin kappa-Chains; D007146:Immunoglobulin lambda-Chains