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Case Report |
Light Chain Dimers in Serum of a Patient with Multiple Myeloma
1 Division of Clinical Biochemistry and Immunology,
2 Department of Biochemistry and Molecular Biology,
3 Department of Molecular Pharmacology and Experimental Therapeutics,
4 Mayo Proteomics Research Center, and
5 Division of Hematology, Department of Internal Medicine, Mayo Clinic, Scottsdale, AZ 85259.
6 Division of Hematology, Department of Internal Medicine, Mayo Clinic, Rochester, MN 55905.
aAddress correspondence to this author at: Division of Clinical Biochemistry and Immunology, 920 Hilton, Mayo Clinic, 200 1st St. SW, Rochester, MN 55905. Fax 507-266-4088; e-mail kyle.robert{at}mayo.edu.
Background: Patients with multiple myeloma often have Bence Jones proteins composed of free monoclonal light chains of the
or
type in their urine. Usually, these light chains exist as monomeric or dimeric forms, but rarely, larger molecules, such as tetramers, have been reported in the serum.
Methods and Results: We report the presence of trimeric complexes of
light chain dimers in a patient who was diagnosed with a free
light chain multiple myeloma 2 years earlier and subsequently underwent a stem cell transplant. Recently, the patient presented with a large serum M-spike (23 g/L) by protein electrophoresis. The spike consisted of monoclonal
light chains without a heavy chain. The urine contained only 8 mg of
light chain in a 24-h specimen. Quantitative analysis of the serum and urinary free light chains (FLCs) indicated the probability of larger aggregates of FLCs. Size-exclusion chromatography, electrophoresis, analytical ultracentrifugation, and mass spectrometric studies of the serum revealed almost exclusively the presence of trimolecular aggregates of
light chain dimers without other multimeric species.
Conclusion: Monoclonal
light chains may present as hexameric aggregates that cannot be cleared by renal excretion.
The following articles in journals at HighWire Press have cited this article:
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I. Herzum, H. Renz, and H. G. Wahl Immunochemical Quantification of Free Light Chains in Urine Clin. Chem., June 1, 2005; 51(6): 1033 - 1035. [Full Text] [PDF] |
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J. R. Tate, D. Gill, R. Cobcroft, and P. E. Hickman Practical Considerations for the Measurement of Free Light Chains in Serum Clin. Chem., August 1, 2003; 49(8): 1252 - 1257. [Abstract] [Full Text] [PDF] |
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R. S. Abraham, S. M. Geyer, T. L. Price-Troska, C. Allmer, R. A. Kyle, M. A. Gertz, and R. Fonseca Immunoglobulin light chain variable (V) region genes influence clinical presentation and outcome in light chain-associated amyloidosis (AL) Blood, May 15, 2003; 101(10): 3801 - 3807. [Abstract] [Full Text] [PDF] |
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