KAPPA AND LAMBDA LIGHT CHAIN MEASUREMENTS
Quantitative Measurement of Light Chains Using IMMAGE Reagents on the IMMAGE 800
Compared to User-Defined Reagents (UDR) on UniCel DxC 600 and Synchron LX20 Systems
INTRODUCTION
UniCel DxC 600 users who run the UDR Kappa Light Chains (KAPX) or Lambda Light Chains (LAMX) reagents
will obtain different values compared to the Beckman Coulter versions of the application (KAP or LAM) run
on an IMMAGE 800. Both Beckman Coulter and the UDR methods use total light chain reagents, measuring
free and bound light chains in serum (or plasma). Both methods also establish traceability to a common
standard. The differences in measured values are due to the differences in the assignment of the equivalent
molecular weights of the kappa and lambda light chains between the methods.
TRACEABILITY
Both the Beckman Coulter and UDR reagent calibrators are traceable to ERM-DA470 (previously called CRM
470).1 Kappa and lambda light chain certified values are not given for ERM-DA470. Instead, the concentrations
are derived from the concentrations of the three major classes of immunoglobulins (IgA, IgG, and IgM).
STANDARDIZATION OF MEASUREMENT
Beckman Coulter kappa and lambda values on IMMAGE 800 are expressed as the “Immunoglobulin
Equivalent Molecular Weight.” It is assumed that the measurement of the light chains is a measurement
of the intact immunoglobulin molecule. Accordingly, the concentration of kappa and lambda is equal to the
concentration of the immunoglobulins.2
[Kappa] + [Lambda] = [IgG] + [IgA] + [IgM]
The UDR reagents for UniCel DxC 600 assays express kappa and lambda values as the “Light Chain Equivalent
Molecular Weight.” It is assumed that the measurement of the light chains is a measurement of only the light
chain portion of the immunoglobulin molecule. The concentration of kappa and lambda is approximately 1/3
the concentration of the immunoglobulins as calculated from the formula described by Lievens.3
COMPARISON OF RESULTS
The calibrator (Plasmaproteins Cal 3x), required for the UDR reagents KAPX and LAMX, has a Lievens
formula assigned value for kappa and lambda. The Beckman Coulter calibrator (Calibrator 1), required for
KAP and LAM, has a Beckman Coulter assigned value for kappa and lambda. Comparison of KAPX or LAMX
on an LX20 or DxC 600 instrument to KAP or LAM on an IMMAGE instrument has been shown to yield an
approximate slope of 0.2 to 0.3, and R value of 0.95. If the Plasmaproteins Cal 3x is assigned a Beckman
Coulter value by running it on an IMMAGE, recalibration and retesting of KAPX or LAMX on a DxC 600 or
LX20 will demonstrate better comparison and regression parameters (slope 1.00 +/- 0.1, R > 0.975).
LAB FORWARD
KAPPA AND LAMBDA LIGHT CHAIN MEASUREMENTS
CORRELATION PLOTS FOR KAPPA AND LAMBDA LIGHT CHAINS
Equivalency between the Synchron LX and UniCel DxC 600/800 Systems has been established. Chemistry results between these systems
are in agreement.
Kappa, IMMAGE KAP vs Synchron LX KAPX
KAPX Calibrator Values According to Lievens
Lambda, IMMAGE LAM vs Synchron LX LAMX
LAMX Calibrator Values According to Lievens
5000
5000
4500
y = 0.235x + 30.67
R2 = 0.946
N = 79, samples run in duplicate
4000
LAMX, Lievens Calibration (mg/dL)
KAPX, Lievens Calibration (mg/dL)
4500
3500
3000
2500
2000
1500
1000
y = 0.363x – 16.46
R2 = 0.908
N = 79, samples run in duplicate
4000
3500
3000
2500
2000
1500
1000
500
500
0
0
1000
0
2000
3000
4000
0
5000
KAP, Beckman Coulter Calibration (mg/dL)
2000
3000
4000
Lambda, IMMAGE LAM vs Synchron LX LAMX
LAMX Calibrator Values According to Beckman Coulter
Kappa, IMMAGE KAP vs Synchron LX KAPX
KAPX Calibrator Values According to Beckman Coulter
5000
5000
4500
LAMX, Beckman Coulter Calibration (mg/dL)
KAPX, Beckman Coulter Calibration (mg/dL)
1000
LAM, Beckman Coulter Calibration (mg/dL)
y = 0.922x + 58.57
R2 = 0.9558
N = 79, samples run in duplicate
4000
3500
3000
2500
2000
1500
1000
500
0
0
1000
2000
3000
4000
KAP, Beckman Coulter Calibration (mg/dL)
5000
4500
y = 0.983x + 17.74
R2 = 0.971
N = 79, samples run in duplicate
4000
3500
3000
2500
2000
1500
1000
500
0
0
1000
2000
3000
4000
LAM, Beckman Coulter Calibration (mg/dL)
SUMMARY
The resulting differences observed between Beckman Coulter and the UDR kappa and lambda reagents are not due to a failure of traceability
or poor correlation of methods. The differences are a result of the differences in assigning the equivalent molecular weights of the analytes.
Users who transition from the Beckman Coulter IMMAGE reagents to the UDR reagents will find good correlation, but a lack of equivalency.
Reference ranges will need to be re-evaluated.
1. Z
egers I, Schreiber W, Sheldon J, Blirup-Jensen S, Munoz A, Merlini G, et al. Certification of proteins in the human serum.
Luxembourg: Office for Official Publications of the European Communities, Joint Research Centre, Institute for Reference Materials
and Measurements; 2008.
2.S
ilverman L. Kappa and lambda light chain measurements. Beckman Instruments Monograph K/L-1 1989.
3. L
ievens MM. Medical and Technical Usefulness of Measurement of Kappa and Lambda Immunoglobulin Light Chains in Serum with an
M-Component. J Clin Chem Clin Biochem 1989; 27:519-523.
Beckman Coulter, the stylized logo, IMMAGE, UniCel and Synchron LX are trademarks of Beckman Coulter Inc.
and are registered in the USPTO.
For Beckman Coulter’s worldwide office locations and phone numbers, please visit
www.beckmancoulter.com/contact
DS-14732B B2013-14587
© 2013 Beckman Coulter, Inc.
www.beckmancoulter.com
PRINTED IN U.S.A.