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Shpitzer D, Cohen YC, Perry C, Melamed G, Alapi H, Reiner-Benaim A, Avivi I. Clinical significance of FLC tests in patients without other evidence of hematologic disorder. Clin Exp Med 2024; 24:198. [PMID: 39180586 PMCID: PMC11344700 DOI: 10.1007/s10238-024-01471-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2024] [Accepted: 08/18/2024] [Indexed: 08/26/2024]
Abstract
The clinical significance of an abnormal free light chain (FLC) test, performed due to unspecific complains in the absence of a known plasma cell dyscrasia (PCD) or lymphoproliferative disease (LPD), is not fully elucidated. We investigated the importance of an abnormal FLC ratio (FLC-R) in this setting. Patients registered in the Maccabi Healthcare Services database, tested for FLC during 2007-2023 without previously documented PCD/LPD or increased total protein (TP) level, were reviewed. Demographics, co-morbidities, and laboratory tests were recorded. FLC-R was defined as normal (0.26-1.65) or slightly (slAb 0.1-0.26/1.65-4), moderately (mAbn 0.1-0.05/4-8) and significantly abnormal (sigAb- < 0.05 or > 8). Factors associated with PCD/LPD and overall survival were identified. In total, 8,661 patients, 2,215 (25.6%) with abnormal FLC-R [2,090 (24.1%)-slAb, 65 (0.75%)-mAbn and 60 (0.7%)-sigAb], were analyzed. Almost none had anemia nor acute renal failure. 14% had concomitant increased immunoglobulins. Within a median follow-up of 52 months, 943 were diagnosed with PCD (816-MGUS, 127-MM/Amyloidosis/plasmacytoma) and 48 with LPD. Median time to PCD and LPD were 19 and 28 months. Multivariate analysis found slAb (HR = 1.8, CI95%:1.53-2.12, p < 0.001), mAbn (HR = 6.3, CI95%:4.16-9.53, p < 0.001), and sigAb FLC (HR = 10.4, CI95%:7.0-15.35, p < 0.001), to be associated with PCD/LPD diagnosis. Decreased IgG, increased IgA, and concomitant comorbidities predicted PCD, whereas increased IgM predicted LPD. Older age, male gender, anemia, decreased albumin, increased IgG and concomitant comorbidities, predicted shorter survival. Our large study emphasizes the independent clinical significance of abnormal FLC-R as a predictor of PCD/LPD diagnosis even in patients with normal TP level, promoting early detection of PCD/LPD.
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Affiliation(s)
- Dor Shpitzer
- Department of Epidemiology, Biostatistics and Community Health Sciences, Faculty of Health Sciences, School of Public Health, Ben Gurion University of the Negev, Beer Sheva, Israel.
| | - Yael C Cohen
- Tel -Aviv Sourasky (Ichilov) Medical Center and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Chava Perry
- Tel -Aviv Sourasky (Ichilov) Medical Center and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Guy Melamed
- Kahn Sagol Maccabi Research & Innovation Center, Maccabi Healthcare Services, Tel Aviv, Israel
| | - Hillel Alapi
- Kahn Sagol Maccabi Research & Innovation Center, Maccabi Healthcare Services, Tel Aviv, Israel
| | - Anat Reiner-Benaim
- Department of Epidemiology, Biostatistics and Community Health Sciences, Faculty of Health Sciences, School of Public Health, Ben Gurion University of the Negev, Beer Sheva, Israel
| | - Irit Avivi
- Tel -Aviv Sourasky (Ichilov) Medical Center and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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Giles HV, Karunanithi K. Performance Characteristics and Limitations of the Available Assays for the Detection and Quantitation of Monoclonal Free Light Chains and New Emerging Methodologies. Antibodies (Basel) 2024; 13:19. [PMID: 38534209 DOI: 10.3390/antib13010019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 02/26/2024] [Accepted: 03/05/2024] [Indexed: 03/28/2024] Open
Abstract
Light chain measurements form an essential component of the testing strategy for the detection and monitoring of patients with suspected and/or proven plasma cell disorders. Urine-based electrophoretic assays remain at the centre of the international guidelines for response assessment but the supplementary role of serum-free light chain (FLC) assays in response assessment and the detection of disease progression due to their increased sensitivity has been increasingly recognised since their introduction in 2001. Serum FLC assays have also been shown to be prognostic across the spectrum of plasma cell disorders and are now incorporated into risk stratification scores for patients with monoclonal gammopathy of undetermined significance (MGUS), smouldering multiple myeloma, and light chain amyloidosis (AL amyloidosis), as well as being incorporated into the criteria for defining symptomatic multiple myeloma. There are now multiple different commercially available serum FLC assays available with differing performance characteristics, which are discussed in this review, along with the implications of these for patient monitoring. Finally, newer methodologies for the identification and characterisation of monoclonal FLC, including modifications to electrophoretic techniques, mass spectrometry-based assays and Amylite, are also described along with the relevant published data available regarding the performance of each assay.
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Affiliation(s)
- Hannah V Giles
- Department of Clinical Haematology, University Hospitals Birmingham NHS Foundation Trust, Birmingham B15 2SY, UK
- Instute of Immunology and Immunotherapy, University of Birmingham, Birmingham B15 2TT, UK
| | - Kamaraj Karunanithi
- Department of Clinical Haematology, University Hospitals North Midlands NHS Trust, Royal Stoke Hospital, Newcastle Road, Stoke-on-Trent ST4 6QG, UK
- School of Medicine, Keele University, Keele, Newcastle-under-Lyme ST5 5BG, UK
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Murray DL. In Reply to Serum Free Light Chain and Drift: Calibrator Adjustment Needed? J Appl Lab Med 2024; 9:396-398. [PMID: 38424718 DOI: 10.1093/jalm/jfad121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 12/11/2023] [Indexed: 03/02/2024]
Affiliation(s)
- David L Murray
- Department of Laboratory Medine and Pathology, Mayo Clinic, Rochester, MN, United States
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Ye Mon M, Ufondu O, Mortley S, Bollag RJ, Singh G. Urine Immunofixation Electrophoresis for Diagnosis of Monoclonal Gammopathy: Evaluation of Methods for Urine Concentration. J Appl Lab Med 2024; 9:350-356. [PMID: 38180079 DOI: 10.1093/jalm/jfad113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 10/16/2023] [Indexed: 01/06/2024]
Abstract
BACKGROUND Examination of urine by immunofixation electrophoresis (UIFE) is one of the tests recommended for screening and monitoring of monoclonal gammopathies, especially multiple myeloma. Unlike the serum free light chain measurement, a positive result on urine immunofixation is diagnostic for monoclonal immunoglobulin light chains. Urine is usually concentrated, generally by membrane filtration, prior to electrophoresis. METHODS Alternative methods to membrane filtration for urine concentration were examined. Residual urine specimens submitted for urine protein electrophoresis were concentrated by precipitation of the proteins by ammonium sulfate salt precipitation, precipitation with ethanol and acetonitrile, and by desiccation. The concentrated specimens were subjected to immunofixation electrophoresis using antisera to free light chains (FLC). The results were compared with those from conventional immunofixation electrophoresis using specimens concentrated by membrane filtration. RESULTS Ammonium sulfate, ethanol, and acetonitrile precipitation results were less than satisfactory. Concentration by desiccation provided results comparable, if not better than, those by membrane filtration and conventional UIFE. The cost of desiccation is minimal compared to more than $5.00/specimen cost of concentration by membrane filtration. The differences in the results with conventional UIFE and the method described here are likely due to (a) variability in the reactivity of different antisera to free monoclonal light chains, and (b) obscuration of monoclonal free light chains by co-migration with intact immunoglobulin monoclonal proteins. CONCLUSIONS Concentrating urine by desiccation for immunofixation electrophoresis is technically simple, inexpensive, and provides results comparable to concentrating by membrane filtration. Using FLC provides a more sensitive assay than using conventional antisera.
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Affiliation(s)
- May Ye Mon
- Department of Pathology, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Obiora Ufondu
- Department of Pathology, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Shanee Mortley
- Department of Pathology, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Roni J Bollag
- Department of Pathology, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Gurmukh Singh
- Department of Pathology, Medical College of Georgia at Augusta University, Augusta, GA, United States
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Singh G, Arinze N, Manthei DM, Plapp FV, Bollag RJ. Urine Protein Immunofixation Electrophoresis: Free Light Chain Urine Immunofixation Electrophoresis Is More Sensitive than Conventional Assays for Detecting Monoclonal Light Chains and Could Serve as a Marker of Minimal Residual Disease. Lab Med 2023; 54:527-533. [PMID: 36857478 DOI: 10.1093/labmed/lmac155] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023] Open
Abstract
BACKGROUND Immunoglobulin monoclonal light chains (MLCs) in serum and urine are markers for monoclonal gammopathy and could serve as markers of minimal residual disease (MRD) in multiple myeloma (MM). Excretion of MLCs in urine is known to result in renal damage and shorter survival in patients with LC-predominant MM. METHODS Retrospective review of urine immunofixation in 1738 specimens at 3 medical centers was conducted to assess the utility of urinalysis for diagnosis and monitoring of monoclonal gammopathy. We tested 228 stored urine specimens via the modified urine immunofixation method, using antisera to assay free LCs (FLCs). RESULTS Our review of urine immunofixation results and medical records validated the theory that the only meaningful value-added finding was detection of monoclonal free light chains. Examination of 228 urine specimens using our novel method revealed 18.4% additional positive results. The rate of incremental findings for lambda LCs was nearly 3-fold higher than for kappa LCs. CONCLUSIONS The new method of urine immunofixation is significantly more sensitive and more efficient than the conventional method for detecting MLCs in urine. The new assay appears to be sensitive enough to prove that MLCs serve as a marker of MRD in MM.
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Affiliation(s)
- Gurmukh Singh
- Department of Pathology Medical College of Georgia at Augusta University, Augusta, GA
| | - Nkechi Arinze
- Department of Pathology Medical College of Georgia at Augusta University, Augusta, GA
| | | | | | - Roni J Bollag
- Department of Pathology Medical College of Georgia at Augusta University, Augusta, GA
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Singh G, Whitaker BM, Wu AHB, Xu H, Bollag RJ. Serum Free Light Chain Quantification Testing: Comparison of Two Methods for Disease Monitoring. J Appl Lab Med 2022; 7:1290-1301. [DOI: 10.1093/jalm/jfac068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 07/01/2022] [Indexed: 11/13/2022]
Abstract
Abstract
Background
Levels of free immunoglobulin light chains in serum and urine are a sensitive measure of dysregulated immunoglobulin synthesis. The development of an assay for free light chains in serum was a major advance in laboratory testing for monoclonal gammopathies. The original assay by The Binding Site, called Freelite®, has been in common use in laboratory monitoring of monoclonal gammopathies. Two clinical entities, myeloma-defining condition and light chain-predominant multiple myeloma, rely on quantitative measurements of serum free light chains.
Methods
Using polyclonal antisera specific to free light chains, Diazyme Laboratories developed a latex immunoturbidimetric assay for quantification of human kappa and lambda serum free light chains. We evaluated the Diazyme assay by comparing the results of kappa and lambda free light chain quantification, and kappa/lambda ratio with the results on the same specimens by the Freelite method. We also compared the correlation of the 2 methods to evaluate response to treatment and to changes in clinical status of patients with multiple myeloma.
Results
The results of Freelite and Diazyme methods are comparable. There was no statistically significant difference in the performance of the 2 assays for quantification of light chains, kappa/lambda ratio, or correlation of clinical parameters from patients with multiple myeloma at various stages of monitoring the disease in 2 geographically diverse laboratory and clinical environments.
Conclusions
The Diazyme method is comparable to Freelite and provides an opportunity to add the test to front-end automation and improvement in efficiency of the assay.
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Affiliation(s)
- Gurmukh Singh
- Department of Pathology, Medical College of Georgia at Augusta University , Augusta, GA 30912 , USA
| | - Brooke M Whitaker
- Department of Pathology, Medical College of Georgia at Augusta University , Augusta, GA 30912 , USA
| | - Alan H B Wu
- Department of Laboratory Medicine, University of California at San Francisco, 1001 Potrero Ave., SFGH 5 , San Francisco CA 94110 , USA
| | - Hongyan Xu
- Department of Population Health Sciences, Medical College of Georgia at Augusta University , Augusta, GA 30912 , USA
| | - Roni J Bollag
- Department of Pathology, Medical College of Georgia at Augusta University , Augusta, GA 30912 , USA
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Giles HV, Wechalekar A, Pratt G. The potential role of mass spectrometry for the identification and monitoring of patients with plasma cell disorders: Where are we now and which questions remain unanswered? Br J Haematol 2022; 198:641-653. [PMID: 35514140 DOI: 10.1111/bjh.18226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 04/08/2022] [Accepted: 04/20/2022] [Indexed: 11/28/2022]
Abstract
Mass spectrometry (MS) techniques provide a highly sensitive methodology for the assessment and monitoring of paraproteins compared to standard electrophoretic techniques. The International Myeloma Working Group (IMWG) recently approved the use of intact light chain matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) in lieu of immunofixation in the clinical assessment of patients and the assessment of patients enrolled on clinical trials. The increased sensitivity of these assays may help to detect and monitor monoclonal proteins (MP) in many patients with previously non-measurable disease, will reduce complete response (CR) rates and increase detection of low-level MP. The ability to track the unique mass or amino acid sequence of the MP also eliminates interference from therapeutic monoclonal antibodies (tmAbs) in most patients with IgG kappa myeloma. The intact light chain assays also provide structural information about the monoclonal light chain, including the presence of N-linked glycosylation, which has been shown to be commoner on amyloidogenic light chains and may have prognostic significance in monoclonal gammopathy of undetermined significance (MGUS). In this review, we discuss these issues alongside differences in the analytical and practical aspects related to the different MS assays under development and the challenges for MS.
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Affiliation(s)
- Hannah V Giles
- University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK.,University of Birmingham, Birmingham, UK
| | - Ashutosh Wechalekar
- Royal Free London NHS Foundation Trust, London, UK.,University College London, London, UK
| | - Guy Pratt
- University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK.,University of Birmingham, Birmingham, UK
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