title: Comparison of Hevylite™ IgA and IgG assay with conventional techniques for the diagnosis and follow-up of plasma cell dyscrasia.
abstract: BACKGROUND
  Heavy/light chain assay allows the characterization and quantification of immunoglobulin light chains bound to heavy chains for each Ig'k and Ig'λ immunoglobulin class, discriminating between the involved/uninvolved isotypes in plasma cell dyscrasia. The Ig'k/Ig'λ ratio (heavy/light chain ratio) enables to monitor the trend of monoclonal component during therapy and disease evolution.
  
  
  OBJECTIVE
  In this study, we evaluate the impact of the heavy/light chain assay in monitoring multiple myeloma patients in comparison with conventional techniques.
  
  
  METHODS
  Serum samples of 28 patients with IgG or IgA monoclonal component were collected for a mean of 109 days and analyzed. The heavy/light chain assay was compared with classical immunoglobulin quantification (Ig'Tot), serum immunofixation electrophoresis, serum protein electrophoresis, and serum-free light chains quantification. Serum samples from 30 healthy patients were used as control (polyclonal).
  
  
  RESULTS
  Heavy/light chain ratio and serum immunofixation electrophoresis were comparable in 86% of the cases, and free light chain ratio and heavy/light chain ratio in 71.8%. Heavy/light chain assay and Ig'Tot measurements showed a concentration-dependent agreement in monoclonal patients. The heavy/light chain assay was able to quantify the monoclonal component migrating in SPE β region: this occurred in 10% of our IgG and 50% of our IgA patients.
  
  
  CONCLUSIONS
  The concordance scores indicate that heavy/light chain and Ig'Tot assays show differences at high monoclonal component values. The heavy/light chain ratio, serum immunofixation electrophoresis, and free light chain ratio showed partial concordance. Our study confirmed that, in the context of heavy/light chain assay, heavy/light chain Ig'k and Ig'λ absolute values and heavy/light chain ratio are both important tools to monitor the presence of monoclonal component that are difficult to be identified in SPE.
authors.affiliation: Department of Molecular and Translational Medicine, Faculty of Medicine, University of Brescia, Brescia, Italy paolinilu@gmail.com.
authors.forename: Lucia
authors.initials: L
authors.lastname: Paolini
authors.affiliation: Department of Molecular and Translational Medicine, Faculty of Medicine, University of Brescia, Brescia, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Di Noto
authors.affiliation: Department of Molecular and Translational Medicine, Faculty of Medicine, University of Brescia, Brescia, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Maffina
authors.affiliation: Department of Molecular and Translational Medicine, Faculty of Medicine, University of Brescia, Brescia, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Martellosio
authors.affiliation: Department of Molecular and Translational Medicine, Faculty of Medicine, University of Brescia, Brescia, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Radeghieri
authors.affiliation: Department of Molecular and Translational Medicine, Faculty of Medicine, University of Brescia, Brescia, Italy.
authors.forename: Caimi
authors.initials: C
authors.lastname: Luigi
authors.affiliation: Department of Molecular and Translational Medicine, Faculty of Medicine, University of Brescia, Brescia, Italy.
authors.forename: Doris
authors.initials: D
authors.lastname: Ricotta
mesh_terms: D004586:Electrophoresis / Q000379:methods / Q000592:standards*; D005500:Follow-Up Studies; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood*; D007074:Immunoglobulin G / Q000097:blood*; D010265:Paraproteinemias / Q000097:blood* / Q000175:diagnosis*
chemical_list: D007070:Immunoglobulin A; D007074:Immunoglobulin G
keywords: Heavy/light chain assay; immunoglobulin; monoclonal component quantification; plasma cell dyscrasia