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Article Dans Une Revue Clinical Chemistry and Laboratory Medicine Année : 2023

Validation of ELISA assays for the calculation of FLC indices for the diagnosis of intrathecal immunoglobulin synthesis

Xavier Heim
  • Fonction : Auteur
Anne Michele Hubert
  • Fonction : Auteur
Issam Raouak
  • Fonction : Auteur
Anthony Charles Nzepa
  • Fonction : Auteur
Jean-Louis Mege
  • Fonction : Auteur
Emilien Delmont
  • Fonction : Auteur
Shahram Attarian
  • Fonction : Auteur
Jean Pelletier
  • Fonction : Auteur
Alexandre Brodovitch
  • Fonction : Auteur
José Boucraut
  • Fonction : Auteur

Résumé

Abstract Objectives Define the cutoff thresholds of the Kappa (K) and Lambda (L) free light chains (FLC) indices for the detection of intrathecal immunoglobulin synthesis (IIS) using the new K and L FLC ELISA from SEBIA. The reference technique, which is not readily standardized between laboratories, is based on the demonstration of oligoclonal banding (OCB) in cerebrospinal fluid (CSF) which is absent in serum. For the past 6 years, we have also routinely calculated the K FLC index using The Binding Site (TBS) reagents on an Optilite instrument, an approach increasingly used as an alternative and/or a complement to electrophoretic analysis. Methods We analyzed 391 serum/CSF pairs divided into three groups. The first group were cases without OCB and with normal albumin CSF/serum ratio (n=174). The second group were cases with specific OCB (n=73). The last group included patients with increased albumin CSF/sera ratio without OCB (n=142). Results Analysis of the first group determined that the cutoffs for detection of IIS are respectively 2.55 and 1.02 for the K FLC and L FLC indices. Of the 73 cases with IIS, only 2 had a K FLC index below this threshold (sensitivity of 97.26%), while 16 out of 73 cases (78.08%) and 13 out of 72 cases (81.94%) had an IgG and L FLC index below the cutoffs, respectively. Additionally, we illustrate equivalent performances for prediction of the presence of OCB between SEBIA and TBS methods. Conclusions Sebia K FLC and L FLC assays are adequate alternative methods for the diagnosis of IIS.
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Dates et versions

hal-04415651 , version 1 (24-01-2024)

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Xavier Heim, Anne Michele Hubert, Issam Raouak, Anthony Charles Nzepa, Jean-Louis Mege, et al.. Validation of ELISA assays for the calculation of FLC indices for the diagnosis of intrathecal immunoglobulin synthesis. Clinical Chemistry and Laboratory Medicine, 2023, 61 (9), pp.1623-1629. ⟨10.1515/cclm-2022-0602⟩. ⟨hal-04415651⟩
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