title: Heavy/light chain specific immunoglobulin ratios provides no additional information than serum proteins electrophoresis and immunofixation for the diagnosis and the follow-up of intact immunoglobulin multiple myeloma patients.
abstract: BACKGROUND
  Serum protein electrophoresis (SPE) and immunofixation electrophoresis (IFE) are used for diagnosis and follow-up of patients with intact immunoglobulin multiple myeloma. However, the numerous limitations of these methods led to the development of a nephelometric immunoassay (Hevylite™) for the specific measurement of serum IgGκ, IgGλ, IgAκ and IgAλ concentrations.
  
  
  METHODS
  In this study, we evaluated the correlation between this assay and SPE and IFE in 114 sera of 15 patients (12 IgG and 3 IgA patients) and its impact on the clinical care of patients, especially for diagnosis, for the evaluation of residual disease and for early detection of relapse.
  
  
  RESULTS
  At inclusion and during follow-up, we found a good correlation between monoclonal immunoglobulin concentrations and SPE (R(2)=0.902 for IgA and R(2)=0.915 for IgG) and nephelometric quantification (R(2)=0.948 for IgA and R(2)=0.920 for IgG) for the evaluation of monoclonal and polyclonal immunoglobulins. Our results illustrate that the Hevylite™ test is less sensitive than the IFE for detection of residual disease: 5 patients who obtained very good partial response or complete response had normalization of the Hevylite™ ratio while IFE was still positive. A relapse had been detectable with the Hevylite™ ratio 1 to 2 months earlier than with SPE and IFE in 3 patients out of 15, but no recommendations for treating patients with only slight biological relapse are available.
  
  
  CONCLUSIONS
  Our results demonstrate that heavy/light chain specific immunoglobulin ratios provides no additional information than serum proteins electrophoresis and immunofixation for the diagnosis and the follow-up of intact immunoglobulin multiple myeloma patients. We also studied the correlation between the concentration of total immunoglobulin measured by Hevylite™ (sum of Ig'κ + Ig'λ) and nephelometric measurement of total IgG or IgA. For this correlation analysis, all 114 sera were analyzed. The correlation coefficient was R(2) = 0.948 for IgA and R(2) = 0.920 for IgG.
authors: Laboratoire de génétique, CHU de Rennes, 35033 Rennes, France.
authors: M-P
authors: MP
authors: Beaumont-Epinette
authors: Laboratoire de biochimie et toxicologie médicale, CHU de Rennes, 35033 Rennes, France; Unité Inserm U991, université de Rennes 1, 35042 Rennes, France.
authors: C
authors: C
authors: Moreau
authors: Service de médecine interne, CHU de Rennes, Hôpital Sud, 16 boulevard de Bulgarie, 35203 Rennes Cedex, France.
authors: S
authors: S
authors: Besnard
authors: Laboratoire de biochimie et toxicologie médicale, CHU de Rennes, 35033 Rennes, France.
authors: F
authors: F
authors: Latute
authors: Laboratoire de biochimie et toxicologie médicale, CHU de Rennes, 35033 Rennes, France.
authors: N
authors: N
authors: Collet
authors: Service de médecine interne, CHU de Rennes, Hôpital Sud, 16 boulevard de Bulgarie, 35203 Rennes Cedex, France.
authors: M
authors: M
authors: Sebillot
authors: Service de médecine interne, CHU de Rennes, Hôpital Sud, 16 boulevard de Bulgarie, 35203 Rennes Cedex, France.
authors: B
authors: B
authors: Grosbois
authors: Laboratoire de biochimie et toxicologie médicale, CHU de Rennes, 35033 Rennes, France; Unité Inserm U991, université de Rennes 1, 35042 Rennes, France.
authors: C
authors: C
authors: Bendavid
authors: Laboratoire de biochimie et toxicologie médicale, CHU de Rennes, 35033 Rennes, France.
authors: L
authors: L
authors: Guenet
authors: Service de médecine interne, CHU de Rennes, Hôpital Sud, 16 boulevard de Bulgarie, 35203 Rennes Cedex, France; UMR CNRS 6290 IGDR, université de Rennes 1, 35042 Rennes, France. Electronic address: Olivier.decaux@chu-rennes.fr.
authors: O
authors: O
authors: Decaux
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001797:Blood Protein Electrophoresis; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007122:Immunoelectrophoresis; D007070:Immunoglobulin A / Q000097:blood*; D007074:Immunoglobulin G / Q000097:blood*; D007143:Immunoglobulin Heavy Chains / Q000097:blood*; D007147:Immunoglobulin Light Chains / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000097:blood* / Q000175:diagnosis / Q000188:drug therapy; D009194:Myeloma Proteins / Q000032:analysis*; D018365:Neoplasm, Residual; D011446:Prospective Studies; D016896:Treatment Outcome
chemical_list: D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; D009194:Myeloma Proteins
keywords: Diagnosis; Diagnostic; Immunofixation; Monitoring; Multiple myeloma; Myélome multiple; Rechute; Relapse; Serum immunofixation; Serum protein electrophoresis; Surveillance; Électrophorèse des protéines sériques