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Clinical Chemistry and Laboratory Medicine (CCLM)

Published in Association with the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM)

Editor-in-Chief: Plebani, Mario

Ed. by Gillery, Philippe / Greaves, Ronda / Lackner, Karl J. / Lippi, Giuseppe / Melichar, Bohuslav / Payne, Deborah A. / Schlattmann, Peter

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Volume 57, Issue 2


Different immunoreactivity of monomers and dimers makes automated free light chains assays not equivalent

Laura Caponi
  • Corresponding author
  • Department of Translational Research and New Technologies in Medicine, University of Pisa, Pisa, Italy
  • Email
  • Other articles by this author:
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/ Elona Koni
  • Department of Translational Research and New Technologies in Medicine, University of Pisa, Pisa, Italy
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  • De Gruyter OnlineGoogle Scholar
/ Nadia Romiti
  • Department of Translational Research and New Technologies in Medicine, University of Pisa, Pisa, Italy
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  • De Gruyter OnlineGoogle Scholar
/ Aldo Paolicchi
  • Department of Translational Research and New Technologies in Medicine, University of Pisa, Pisa, Italy
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  • De Gruyter OnlineGoogle Scholar
/ Maria Franzini
  • Department of Translational Research and New Technologies in Medicine, University of Pisa, Pisa, Italy
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
Published Online: 2018-07-23 | DOI: https://doi.org/10.1515/cclm-2018-0412



The automated immunochemical serum free light chains (FLC) assays, Freelite (a polyclonal antiserum) and N Latex FLC (a mixture of monoclonal antibodies), are not interchangeable, as they may provide different results on a same sample. This study was aimed to establish if the calibrators contain FLC oligomers, and if different reactivity against monomers and dimers contributes to the discrepancy.


Gel filtration chromatography fractions of the calibrators were subjected to a Western blot (WB) and analyzed by each reagent. The procedure was repeated after pretreating the N Latex FLC calibrator with the reducing agent dithiothreitol (DTT).


Both calibrators contain FLC dimers and monomers. Both reagents detect (with different sensitivity) FLC kappa monomers and dimers; instead, Freelite detects only FLC lambda dimers, while N Latex FLC detects only FLC monomers. After DTT treatment, only the N Latex lambda still detects FLC with reduced protein thiols, while the reactivity of all other reagents is abolished.


Due to their different reactivity against FLC monomers and oligomers, the Freelite and N Latex FLC are calibrated against different components of their own calibrators, making the two reagents not equivalent. The redox status of FLC determines the immunoreactivity not only of FLC dimers, but also of the monomers.

Keywords: disulfide bonds; free light chains; monoclonal gammopathies; monomers and oligomers


  • 1.

    Rajkumar SV, Dimopoulos MA, Palumbo A, Blade J, Merlini G, Mateos MV, et al. International Myeloma Working Group updated criteria for the diagnosis of multiple myeloma. Lancet Oncol 2014;15:e538–48.Web of ScienceCrossrefGoogle Scholar

  • 2.

    Graziani MS, Merlini G. Serum free light chain analysis in the diagnosis and management of multiple myeloma and related conditions. Expert Rev Mol Diagn 2014;14:55–66.PubMedWeb of ScienceCrossrefGoogle Scholar

  • 3.

    Jenner E. Serum free light chains in clinical laboratory diagnostics. Clin Chim Acta 2014;427:15–20.Web of ScienceCrossrefPubMedGoogle Scholar

  • 4.

    Mollee P, Tate J, Pretorius CJ. Evaluation of the N Latex free light chain assay in the diagnosis and monitoring of AL amyloidosis. Clin Chem Lab Med 2013;51:2303–10.Web of ScienceGoogle Scholar

  • 5.

    Kim HS, Kim HS, Shin KS, Song W, Kim HJ, Kim HS, et al. Clinical comparisons of two free light chain assays to immunofixation electrophoresis for detecting monoclonal gammopathy. Biomed Res Int 2014;647238:1–7.Web of ScienceGoogle Scholar

  • 6.

    Carr-Smith HD, Jenner EL, Evans JA, Harding SJ. Analytical issues of serum free light chain assays and the relative performance of polyclonal and monoclonal based reagents. Clin Chem Lab Med 2016;54:997–1003.Web of SciencePubMedGoogle Scholar

  • 7.

    Caponi L, Franzini M, Koni E, Masotti S, Petrini M, Paolicchi A. Discrepancy between FLC assays: only a problem of quantification? Clin Chem Lab Med 2016;54:1111–3.Web of ScienceGoogle Scholar

  • 8.

    Bossuyt X, Delforge M, Reynders M, Dillaerts D, Sprangers B, Fostier K, et al. Diagnostic thresholds for free light chains in multiple myeloma depend on the assay used. Leukemia 2017. doi: 10.1038/leu.2017.335. [Epub ahead of print].Web of SciencePubMedGoogle Scholar

  • 9.

    Di Noto G, Cimpoies E, Dossi A, Paolini L, Radeghieri A, Caimi L, et al. Polyclonal versus monoclonal immunoglobulin-free light chains quantification. Ann Clin Biochem 2015;52:327–36.PubMedCrossrefWeb of ScienceGoogle Scholar

  • 10.

    Kaplan B, Ramirez-Alvarado M, Sikkink L, Golderman S, Dispenzieri A, Livneh A, et al. Free light chains in plasma of patients with light chain amyloidosis and non-amyloid light chain deposition disease. High proportion and heterogeneity of disulfide-linked monoclonal free light chains as pathogenic features of amyloid disease. Br J Haematol 2009;144:705–15.CrossrefPubMedWeb of ScienceGoogle Scholar

  • 11.

    Kaplan B, Golderman S, Aizenbud B, Esev K, Kukuy O, Leiba M, et al. Immunoglobulin-free light chain monomer-dimer patterns help to distinguish malignant from premalignant monoclonal gammopathies: a pilot study. Am J Hematol 2014;89:882–8.CrossrefPubMedWeb of ScienceGoogle Scholar

  • 12.

    te Velthuis H, Knop I, Stam P, van den Broek M, Bos HK, Hol S, et al. N Latex FLC – new monoclonal high-performance assays for the determination of free light chain kappa and lambda. Clin Chem Lab Med 2011;49:1323–32.Web of SciencePubMedGoogle Scholar

  • 13.

    Baden EM, Owen BA, Peterson FC, Volkman BF, Ramirez-Alvarado M, Thompson JR. Altered dimer interface decreases stability in an amyloidogenic protein. J Biol Chem 2008;283:15853–60.CrossrefWeb of ScienceGoogle Scholar

  • 14.

    Palladini G, Jaccard A, Milani P, Lavergne D, Foli A, Bender S, et al. Circulating free light chain measurement in the diagnosis, prognostic assessment and evaluation of response of AL amyloidosis: comparison of Freelite and N latex FLC assays. Clin Chem Lab Med 2017;55:1734–43.Web of ScienceGoogle Scholar

  • 15.

    Pretorius CJ, Klingberg S, Tate J, Wilgen U, Ungerer JP. Evaluation of the N Latex FLC free light chain assay on the Siemens BN analyser: precision, agreement, linearity and variation between reagent lots. Ann Clin Biochem 2012;49:450–5.CrossrefWeb of ScienceGoogle Scholar

  • 16.

    Hoedemakers RM, Pruijt JF, Hol S, Teunissen E, Martens H, Stam P, et al. Clinical comparison of new monoclonal antibody-based nephelometric assays for free light chain kappa and lambda to polyclonal antibody-based assays and immunofixation electrophoresis. Clin Chem Lab Med 2011;50:489–95.PubMedGoogle Scholar

  • 17.

    Lock RJ, Saleem R, Roberts EG, Wallage MJ, Pesce TJ, Rowbottom A, et al. A multicentre study comparing two methods for serum free light chain analysis. Ann Clin Biochem 2013;50:255–61.CrossrefWeb of SciencePubMedGoogle Scholar

  • 18.

    Messiaen AS, De Sloovere MM, Claus PE, Vercammen M, Van Hoovels L, Heylen O, et al. Performance evaluation of serum free light chain analysis: nephelometry vs turbidimetry, monoclonal vs polyclonal reagents. Am J Clin Pathol 2017;147:611–22.Web of SciencePubMedCrossrefGoogle Scholar

  • 19.

    Palumbo A, Rajkumar SV, San Miguel JF, Larocca A, Niesvizky R, Morgan G, et al. International Myeloma Working Group consensus statement for the management, treatment, and supportive care of patients with myeloma not eligible for standard autologous stem-cell transplantation. J Clin Oncol 2014;32:587–600.CrossrefWeb of ScienceGoogle Scholar

About the article

Corresponding author: Laura Caponi, MD, PhD, Department of Translational Research and New Technologies in Medicine, Laboratory of Clinical Pathology, University Hospital of Pisa, Building 43, Via Roma, 67, 56126 Pisa, Italy

Received: 2018-04-20

Accepted: 2018-06-25

Published Online: 2018-07-23

Published in Print: 2018-12-19

Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

Research funding: Institutional funding of University of Pisa.

Employment or leadership: None declared.

Honorarium: None declared.

Competing interests: The funding organization played no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication.

Citation Information: Clinical Chemistry and Laboratory Medicine (CCLM), Volume 57, Issue 2, Pages 221–229, ISSN (Online) 1437-4331, ISSN (Print) 1434-6621, DOI: https://doi.org/10.1515/cclm-2018-0412.

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