Analytical issues of serum free light chain assays and the relative performance of polyclonal and monoclonal based reagents
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Hugh D. Carr-Smith
,
Ellen L. Jenner
Abstract
Serum free light chain (FLC) assays have been incorporated into routine clinical practice and their use is recommended in international guidelines for the management of monoclonal gammopathies. Given that FLCs are not simple analytes, laboratories should be aware of potential analytical issues when using FLC assays, including antigen excess, lot-to-lot variation and non-linearity. Whilst manufacturers of monoclonal antibody-based assays claim that they overcome such issues, the evidence available to date does not support this. Here we review and compare the technical performance of both polyclonal and monoclonal antibody-based assays. The evidence suggests that the Freelite assay, based on polyclonal antisera, gives a broader recognition of monoclonal FLCs than the N Latex assay, based on monoclonal antisera, and despite being cited as a technical concern, we show that lot-to-lot variation of the Freelite assay is good. Both non-linearity and antigen excess are characteristic of FLC analysis and laboratories should be aware of these phenomena regardless of the assay system they use. Comparisons of the absolute values of sFLCs determined using monoclonal and polyclonal antibody-based assays show poor quantitative agreement and, because current guidelines have been established using the polyclonal antibody-based Freelite assay, it should not be assumed that assays utilizing monoclonal antibodies will give compliance with these guidelines.
References
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©2016 by De Gruyter
Articles in the same Issue
- Frontmatter
- Editorial
- Protein electrophoresis and serum free light chains in the diagnosis and monitoring of plasma cell disorders: laboratory testing and current controversies
- Laboratory Testing as Recommended by the Guidelines and the International Myeloma Working Group
- Laboratory testing requirements for diagnosis and follow-up of multiple myeloma and related plasma cell dyscrasias
- Free light chain testing for the diagnosis, monitoring and prognostication of AL amyloidosis
- Laboratory testing in monoclonal gammopathy of renal significance (MGRS)
- The impact of renal function on the clinical performance of FLC measurement in AL amyloidosis
- Serum and Urine Protein Electrophoresis and Immunofixation Testing
- Challenges of measuring monoclonal proteins in serum
- Screening immunofixation should replace protein electrophoresis as the initial investigation of monoclonal gammopathy: Point
- Should routine laboratories stop doing screening serum protein electrophoresis and replace it with screening immune-fixation electrophoresis? No quick fixes: Counterpoint
- Moving towards harmonized reporting of serum and urine protein electrophoresis
- Multiple qualitative and quantitative methods for free light chain analysis are necessary as first line tests for AL amyloidosis
- Use of isoelectric focusing to discriminate transient oligoclonal bands from monoclonal protein in treated myeloma
- New patterns of relapse in multiple myeloma: a case of “light chain escape” in which FLC predicted relapse earlier than urine and serum immunofixation
- Serum Free Light Chain Methods and Controversies
- Analytical issues of serum free light chain assays and the relative performance of polyclonal and monoclonal based reagents
- Measurement of free light chains with assays based on monoclonal antibodies
- Measurement of free light chains – pros and cons of current methods
- Is accuracy of serum free light chain measurement achievable?
- Performance goals for immunoglobulins and serum free light chain measurements in plasma cell dyscrasias can be based on biological variation
- A patient with AL amyloidosis with negative free light chain results
- Strengths and weaknesses of methods for identifying monoclonal free light chains of Ig: examples from two cases with renal disease
- Comparison of Freelite™ and N Latex serum free light chain assays in subjects with end stage kidney disease on haemodialysis
- New Laboratory Assays and Challenges
- Quantification of β-region IgA monoclonal proteins – should we include immunochemical Hevylite® measurements? Point
- Quantification of β region IgA paraproteins – should we include immunochemical “heavy/light chain” measurements? Counterpoint
- Free light chains and heavy/light chains in monitoring POEMS patients
- Monitoring free light chains in serum using mass spectrometry
- Monoclonal antibody therapeutics as potential interferences on protein electrophoresis and immunofixation
- Monitoring multiple myeloma patients treated with daratumumab: teasing out monoclonal antibody interference
- Interference of daratumumab in monitoring multiple myeloma patients using serum immunofixation electrophoresis can be abrogated using the daratumumab IFE reflex assay (DIRA)
- Letter to the Editor
- Discrepancy between FLC assays: only a problem of quantification?
Articles in the same Issue
- Frontmatter
- Editorial
- Protein electrophoresis and serum free light chains in the diagnosis and monitoring of plasma cell disorders: laboratory testing and current controversies
- Laboratory Testing as Recommended by the Guidelines and the International Myeloma Working Group
- Laboratory testing requirements for diagnosis and follow-up of multiple myeloma and related plasma cell dyscrasias
- Free light chain testing for the diagnosis, monitoring and prognostication of AL amyloidosis
- Laboratory testing in monoclonal gammopathy of renal significance (MGRS)
- The impact of renal function on the clinical performance of FLC measurement in AL amyloidosis
- Serum and Urine Protein Electrophoresis and Immunofixation Testing
- Challenges of measuring monoclonal proteins in serum
- Screening immunofixation should replace protein electrophoresis as the initial investigation of monoclonal gammopathy: Point
- Should routine laboratories stop doing screening serum protein electrophoresis and replace it with screening immune-fixation electrophoresis? No quick fixes: Counterpoint
- Moving towards harmonized reporting of serum and urine protein electrophoresis
- Multiple qualitative and quantitative methods for free light chain analysis are necessary as first line tests for AL amyloidosis
- Use of isoelectric focusing to discriminate transient oligoclonal bands from monoclonal protein in treated myeloma
- New patterns of relapse in multiple myeloma: a case of “light chain escape” in which FLC predicted relapse earlier than urine and serum immunofixation
- Serum Free Light Chain Methods and Controversies
- Analytical issues of serum free light chain assays and the relative performance of polyclonal and monoclonal based reagents
- Measurement of free light chains with assays based on monoclonal antibodies
- Measurement of free light chains – pros and cons of current methods
- Is accuracy of serum free light chain measurement achievable?
- Performance goals for immunoglobulins and serum free light chain measurements in plasma cell dyscrasias can be based on biological variation
- A patient with AL amyloidosis with negative free light chain results
- Strengths and weaknesses of methods for identifying monoclonal free light chains of Ig: examples from two cases with renal disease
- Comparison of Freelite™ and N Latex serum free light chain assays in subjects with end stage kidney disease on haemodialysis
- New Laboratory Assays and Challenges
- Quantification of β-region IgA monoclonal proteins – should we include immunochemical Hevylite® measurements? Point
- Quantification of β region IgA paraproteins – should we include immunochemical “heavy/light chain” measurements? Counterpoint
- Free light chains and heavy/light chains in monitoring POEMS patients
- Monitoring free light chains in serum using mass spectrometry
- Monoclonal antibody therapeutics as potential interferences on protein electrophoresis and immunofixation
- Monitoring multiple myeloma patients treated with daratumumab: teasing out monoclonal antibody interference
- Interference of daratumumab in monitoring multiple myeloma patients using serum immunofixation electrophoresis can be abrogated using the daratumumab IFE reflex assay (DIRA)
- Letter to the Editor
- Discrepancy between FLC assays: only a problem of quantification?
