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Articles |
1
Department of Immunology, The Medical School, Edgbaston, Birmingham B15 2TT, United Kingdom.
2
The Binding Site, PO Box 4073, Birmingham B29 6AT,
United Kingdom.
a Author for correspondence. E-mail
a.r.bradwell{at}bham.ac.uk.
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
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and 
free light chains (FLCs) are important markers for
identifying and monitoring many patients with B-cell tumors. Automated
immunoassays that measure FLCs in urine and serum have considerable
clinical potential.
Methods: Sheep antibodies, specific for FLCs, were prepared by
immunization with pure and molecules and then adsorbed
extensively against whole immunoglobulins. The antibodies were
conjugated onto latex particles and used to assay and FLCs on
the Beckman IMMAGETM protein analyzer.
Results: The unconjugated antibodies showed minimal
cross-reactivity with intact immunoglobulins or other proteins. With
latex-conjugated antibodies, and FLCs could be measured in
normal sera and most normal urine samples. Patients with multiple
myeloma had increased concentrations of the relevant serum FLC, whereas
both FLCs were increased in the sera of patients with systemic lupus
erythematosus.
Conclusions: We developed sensitive, automated immunoassays for
and FLC measurements in serum and urine that should facilitate
the assessment of patients with light chain abnormalities.
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Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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or free light chain (FLC) molecules that are
produced by malignant clones of B cells. BJ proteins are used as cancer
markers for identifying and monitoring patients with B-cell lineage
tumors, (e.g., multiple myeloma) and for characterizing light chain
amyloidosis. Urine is the usual test fluid and typically is
concentrated and then analyzed by protein electrophoresis (PE) or
immunofixation electrophoresis (IFE) (1). Such techniques
are time-consuming and can be inaccurate. Furthermore, the amounts of
FLCs entering the urine are strongly influenced by renal tubular
function. An alternative approach is to measure FLC concentrations in serum. Studies have shown that when urine concentrations are increased, there is a corresponding increase in the serum of the same FLC (2) and the latter may be diagnostically more accurate if patients have renal failure (3). However, immunoassays must be highly specific because serum concentrations of FLCs are several orders of magnitude lower than those of the light chains bound to intact immunoglobulins.
Early serum immunoassays involved separating FLCs from intact immunoglobulins before analysis (4)(5)(6), and although accurate, they were impractical for routine use. Subsequent assays have used antibodies directed against the "hidden" epitopes of FLC molecules that are located at the interface between the light and heavy chains of intact immunoglobulins. Previous studies used RIAs and enzyme immunoassays with polyclonal antisera against FLCs to analyze urine samples, but the specificity was inadequate for serum measurements (7)(8), and variations in light chain polymerization caused measurement errors (9)(10).
The use of monoclonal antibodies appears to be an obvious approach to improving specificity, but such antibodies have been difficult to develop (11)(12)(13)(14), and their use has been restricted to RIAs and enzyme immunoassays, which are more complicated than turbidimetric techniques and therefore not ideal for routine immunochemistry laboratories. Attempts were made to develop turbidimetric (15) and latex-enhanced nephelometric assays (16) using polyclonal antibodies, but they were insufficiently sensitive to detect serum or urine FLC concentrations within normal reference values, and cross-reactivity with intact immunoglobulins was unacceptable.
In this study, we describe the development and assessment of sensitive,
latex-enhanced, turbidimetric, FLC assays for use on the Beckman
IMMAGETM that can accurately measure and
FLCs in serum and urine. The detection limit is compared with existing
clinical laboratory tests for FLCs, and their potential in the clinical
laboratory is discussed.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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or molecules that had been
purified from urine samples containing BJ proteins. The resulting
antisera were adsorbed against purified myeloma IgG, IgA, and IgM
proteins and then affinity purified against mixtures of the respective
FLCs immobilized onto CNBr-activated Sepharose 4B (Amersham Pharmacia
Biotech).
Specificity was evaluated by (a) immunoelectrophoresis
against BJ proteins and pooled normal human serum; (b)
hemagglutination assays using sheep red blood cells sensitized with
individual FLCs, purified polyclonal IgG, monoclonal IgA, or monoclonal
IgM (17); (c) Western blot analysis comparing the
staining of whole serum and urine blots produced by the polyclonal FLC
antisera with monoclonal antibodies recognizing free and bound
(clone GD12; The Binding Site Ltd.) and molecules (clone 312H;
Department of Immunology, University of Birmingham, Birmingham, United
Kingdom).
To assess antibody reactivity against FLC monomers and dimers, urine
samples containing both forms of and BJ proteins were separated
on Sephadex G-100 (Amersham Pharmacia) in Tris-buffered saline, pH 7.4.
Monomer and dimer fractions were then tested against the FLC antisera
and whole light chain antisera by radial immunodiffusion (RID). In
addition, FLC monomers and dimers in the urine samples were separated
by nonreducing sodium dodecyl sulfate-polyacrylamide gel
electrophoresis (SDS-PAGE). These gels were blotted and probed with the
polyclonal FLC antisera.
FLC-specific antisera were digested with pepsin to produce F(ab)2 fractions, which were adsorbed onto 184-nm polystyrene latex particles (18). The latex-conjugated reagents were tested for specificity by nephelometry on the Beckman IMMAGE, and antisera requiring further adsorption were recycled through the adsorption and testing procedures until satisfactory.
flc reference material
Monomeric, polyclonal FLC and molecules were prepared by
reduction and acetylation of polyclonal IgG that was purified from a
serum pool prepared by combining sera collected from 200 apparently
healthy donors. Acetylated FLCs were purified on a Sephadex
G-100 column. and molecules were then separated using protein L
(Actigen Ltd), which specifically binds only chains
(19), and further purified by affinity chromatography
against specific polyclonal antibodies. FLC purity was assessed using
silver-stained SDS-PAGE gels, dot blot, and hemagglutination inhibition
assays. Protein concentrations were determined by the
BCATM protein assay (Pierce).
Because of the limited amount of primary reference material, secondary
reference materials were required, which were prepared from pools of
nine and seven BJ proteins. However, these monoclonal proteins
were not considered ideal for use as a working calibrator. Therefore, a
third reference material was prepared that comprised serum from a
patient with systemic lupus erythematosus (SLE) that contained
increased polyclonal FLCs. The pure FLC preparations were used to
assign and values to the secondary reference preparations by
RID, which were then used to assign FLC values to the SLE serum
preparation by nephelometry on the Beckman IMMAGE. Each stage of the
value transfer was completed at three dilutions and repeated three
times. All protein preparations were frozen and stored at -20 °C
until required.
nephelometric assay of FLCs on the beckman immage
Both and assays used the noncompetitive, near-infrared,
particle immunoassay protocol on the instrument. A six-point
calibration curve with a third-order polynomial curve fit was used. The
assay components were as follows: 15 µL of serum sample for and
21 µL for , 60 µL of latex reagent, 5 µL of 120 g/L
polyethylene glycol 6000 (final concentration, 2 g/L), and 195
µL of phosphate-buffered saline. The reaction time for each assay was
6 min with a serum dilution of 1:10. Susceptibility to interference was
assessed by adding known concentrations of purified whole
immunoglobulins, triglycerides, hemoglobin, and bilirubin (Fig. 1
) to base serum samples containing concentrations of FLCs just
above the upper limit of normal (20–40 mg/L). Analysis was based on a
paired difference protocol as proposed by the NCCLS
(20). Each sample and the controls were analyzed three
times, and the mean difference and 95% confidence intervals were
calculated (Fig. 1
). For rheumatoid factor (RF), a serum sample
containing 1100 kIU/L RF activity was assayed for FLCs,
undiluted and at different dilutions, and the results were compared.
Assay precision was assessed by repeat assay of serum samples
containing three different concentrations of FLCs. Intraassay precision
was determined by repeat assay of the samples 15 times using a single
calibration curve, interassay precision was determined by measuring the
samples once using each of 10 separate calibration curves, and total
assay precision was determined by measuring the samples five times
using three separate calibration curves. Assay linearity was determined
by serial dilution of serum samples, containing known amounts of FLCs,
into Tris-buffered saline.
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limits of detection of pe and ife for FLCs
The detection limits of nephelometry, PE, and IFE for measuring
FLCs were compared. For serum, different concentrations of
purified monoclonal and FLCs were added to a normal serum that
was subjected to PE and IFE. For urine, the same and proteins
were added to a normal urine that had been concentrated 100-fold using
a MiniconTM (Amicon), and the mixture was
subjected to PE and IFE.
comparison of urine flc measurements by nephelometry and rid
Twenty-four urine samples containing and 22 samples containing
BJ proteins were assayed for FLCs by RID and nephelometry. The
antisera used in the RID assays reacted against whole light chains, but
large amounts of anti-IgG, -IgA, and -IgM heavy chain antisera were
added to prevent spurious whole immunoglobulin precipitate rings. In
practice, this produced assays that were specific for FLCs in urine
samples.
reference values
FLC concentrations were measured by nephelometry in the serum of
50 male (mean age, 43.2 years; range, 19–71 years) and 50 female (mean
age, 42.4 years; range, 17–59 years) blood donors. For urine reference
values, FLC concentrations were measured in mid-stream, early-morning
urine samples from 36 healthy men (mean age, 35.1 year; range, 18–54
years) and 30 healthy women (mean age, 33.1 year; range, 18–52 years).
Sodium azide (1 g/L) was added to all samples, which were
stored at -20 °C until analysis (21).
patient studies
To produce a preliminary assessment of the assays in a clinical
setting, the following groups were studied: 21 patients with multiple
myeloma, 6 with Waldenstrom macroglobulinemia, 6 with FLC
myeloma, and 12 patients with SLE.
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Results |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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FLC antibodies reacted with -labeled cells at
a dilution >1:16 000 and at 
1:2 against polyclonal IgG, monoclonal
IgA and IgM, and monoclonal FLC-coated cells. antibodies
reacted with -labeled cells at a dilution>1:16 000 and at
1:2 against polyclonal IgG, monoclonal IgA and IgM, and
monoclonal FLC-coated cells. In Western blots, both FLC antisera
reacted strongly with two closely migrating bands at 25 000–30 000
kDa and weakly with several larger and smaller molecular mass
bands. Similar staining patterns were observed with the monoclonal
antibodies (Fig. 2
). The polyclonal antibodies detected both monomers and dimers
of FLCs by Western blot (Fig. 2
). By RID, both and FLC antisera
produced precipitation rings against the monomers and dimers and in
similar proportions.
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flc reference materials
Each FLC preparation was found to be >99% pure by silver-stained
SDS-PAGE, and the other FLC was not detected by hemagglutination
inhibition or dot blot. The data from the value transfers showed that
the assays exhibited good linearity with all results being within 5.3%
of the mean assigned values. The final FLC values for the reference
preparations derived from the SLE serum were 46 mg/L for and 71.4
mg/L for . These calibration values were used throughout the study.
assay conditions on the beckman immage
When the assay conditions had been optimized (see Materials
and Methods), the assay range was 3.6–172 mg/L for serum free
and 5.6–268 mg/L for . The detection limits for undiluted
urine samples were 0.36 and 0.56 mg/L, respectively. The assays did not
demonstrate antigen excess when tested up to 40 g/L for FLCs and to
60 g/L for FLCs.
The interference studies for the FLC assay showed slight
cross-reactivity with whole immunoglobulins, whereas all other
substances had little effect on either assay (Fig. 1
). There was modest
interference by RF. The initial value for free in the undiluted RF
sample (1100 kIU/L was 13.4 mg/L and changed to 13.7 and 12.5 mg/L at
1:2 and 1:4, respectively (corrected for dilution). The undiluted RF
sample also contained 12.8 mg/L free , which changed to 15.2 and
16.5 mg/L at 1:2 and 1:4, respectively (corrected for dilution).
Assay imprecision, expressed as the CV, was as follows. For
free at 7.3, 29.7, and 114 mg/L, the intraassay CV was 3.8%,
2.1%, and 2.9%, respectively; the interassay CV was 9.2%, 5.0%, and
3.5%, respectively; and the total assay CV was 8.2%, 5.2%, and
2.7%, respectively. For free at 15.8, 62.4 and 227 mg/L, the
intraassay CV was 4.7%, 1.9%, and 1.9%, respectively; the interassay
CV was 7.6%, 2.9%, and 4.0%, respectively; and the total assay CV
was 9.5%, 5.2%, and 4.1%, respectively. Linearity studies showed
that the free assay was linear at 3.6–172 mg/L (p
= 0.9996; y = 1.03x - 1.6
mg/L) and the free assay was linear at 5.6–268 mg/L
(p = 0.9995; y = 1.00x
- 0.5 mg/L).
comparison of flc detection by electrophoresis, ife, and rid
A BJ protein migrating toward the anode
(ß2 position) could be detected by PE at 2000
mg/L, and a BJ protein migrating toward the cathode (
mobility)
could be detected at 500 mg/L. The differences in detection limits were
attributable to masking of the monoclonal band by ß globulins
(transferrin and complement component C3). The same BJ proteins added
to urine concentrated 100-fold showed similar detection limits, 20 and
5 mg/L, respectively, when compared with nonconcentrated urines. By
IFE, the detection limits were 150 mg/L for and 100 mg/L for ,
and were similar for serum and urine samples. Comparison of FLC
measurement by RID and turbidimetry showed a high degree of correlation
for both (p = 0.99; y =
1.15x - 15.2 mg/L) and assays (p =
0.98; y = 0.92x - 31.2 mg/L).
normal serum and urine results
The mean (± SD) concentration of serum free was 8.4 ±
2.66 mg/L (n = 100; range, 3.6–15.9 mg/L; 95% confidence
interval, 4.2–13.1 mg/L), for free , the mean (± SD) concentration
was 14.5 ± 4.4 mg/L (n = 100; range, 8.1–33 mg/L; 95%
confidence interval, 9.2–22.7 mg/L). The mean serum : ratio was
1:1.67 (95% confidence interval, 1:2.78–1:0.99; Fig. 3
).%For urine, the mean (± SD) free concentration was 5.4 ± 4.95
mg/L (n = 66; range, 0.36–20.3 mg/L; 95% confidence interval,
0.39–15.1 mg/L), and the mean (± SD) free concentration was
3.17 ± 3.3 mg/L (n = 66; range, 0.81–17.3 mg/L; 95%
confidence interval, 0.81–10.1 mg/L). The mean : ratio was
1:0.54 (95% confidence interval, 1:2.17–1:0.25). There were no
differences between serum or urine free or results on the basis
of age or sex. The mean, normal urine FLC excretion was 3.7 mg/g of
creatinine for and 2.0 mg/g of creatinine for . There was a
positive but nonsignificant correlation of urine creatinine
concentrations with (r = 0.22) and
(r = 0.17) measurements.
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patient samples
Sera from patients with multiple myeloma or Waldenstrom
macroglobulinemia who had intact monoclonal immunoglobulins contained
increased concentrations of the relevant FLCs (Fig. 4
). In all but one sample, the nonclonal light chains had normal
or reduced concentrations. All of the sera from patients with BJ
myeloma had increased serum concentrations of the relevant FLC and
normal concentrations of the other FLC (Table 1
). Two of these patients were in clinical remission with no FLCs
detected in the urine by RID assay (<40 mg/L), but both had increased
serum FLC concentrations with abnormal : ratios. Sera from
patients with SLE showed increases of both FLC, and : ratios were
within the reference interval (Fig. 4
).
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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FLC assay could be improved (Fig. 1
). Such an improvement might produce a slight reduction of the
reference interval. The concentrations of FLCs in normal sera
were comparable with previously published values (Table 2
), although values were higher than . Because there are
approximately twice as many - as -producing lymphoid cells, this
result may seem rather surprising. However, a similar observation was
made in a recent study (14), and it was suggested that in
healthy individuals, FLC production might be less than . An
alternative explanation is that because molecules usually are
monomeric (25 kDa), renal clearance is faster than for the dimeric
molecules (50 kDa). In a study on the movement of dextran polymers
across capillary membranes, it was shown that molecules of 20 kDa were
cleared 3.2 times faster than 37-kDa molecules (22). Our
results show a : clearance rate of 3 x [( urine/
urine)/( serum/ serum)]. Although polysaccharides are different
in charge, shape, and flexibility from globular proteins of similar
molecular weight, differential filtration could account for our
results. This may not have been observed in some of the early FLC
studies because of the poor specificity of the antisera (see below). In
urine, the concentrations of both FLCs were slightly higher than noted
previously, whereas : ratios were similar to other studies. The
higher FLC concentrations can be explained by our use of early-morning
urine samples, which are typically two- to threefold more concentrated
than 24-h urine samples.
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Table 2
shows that assays using monoclonal antibodies have produced
rather varied results. One report showed rather low (12) and
another high (14) FLC concentrations in normal sera. It is
unclear whether the variation is attributable to specificity,
calibration, or matrix differences. However, comparison must await
internationally accepted reference materials.
It is of note that the mean concentrations of the nonclonal FLCs in myeloma sera were lower than previous reports, suggesting improved specificity of the antisera (7)(13). One sample, containing an IgM monoclonal protein, had increased concentrations of the nonclonal FLCs. This result can be explained by a matrix effect, but a degree of cross-reactivity with whole immunoglobulins cannot be excluded.
Polymerization of FLC molecules could lead to errors in quantification.
Whereas Sölling et al. (23) indicated that both
monomers and dimers of FLCs were detected equally using antibodies
against whole light chains, another study (10) showed that
FLC antibodies failed to detect monomers satisfactorily, possibly
because of low-affinity antisera. Our preliminary experiments showed
similar detection of both monomers and dimers, but further studies are
required. It might be difficult to develop FLC assays that measure all
forms of the molecules equally, so perfect quantification could remain
elusive.
The turbidimetric assays were at least 500 times more sensitive than serum or urine electrophoresis. Even with the use of high-resolution electrophoresis (24) and taking account of the focusing effect of monoclonal proteins on electrophoresis gels, the FLC immunoassays had detection limits >50-fold lower than electrophoresis and perhaps 20-fold lower than IFE. These substantially lower detection limits should allow early identification of patients with abnormal FLC production.
clinical role of flc immunoassays
Serum and urine FLC immunoassays should be useful for identifying
and monitoring patients with BJ myeloma and nonsecretory myeloma
(25). The assays might also find use in establishing light
chain clonality and for monitoring patients with whole
immunoglobulin-secreting multiple myeloma, light chain amyloidosis, and
other diseases associated with excess monoclonal light chain production
(26). FLC quantification may also be of interest in
assessing patients with chronic B-cell activation. Polyclonal FLC
concentrations are increased in autoimmune diseases such as SLE
(27)(28) and insulin-dependent diabetes
(29), and in chronic inflammatory diseases such as
sarcoidosis and tuberculosis (30). They are also increased
in the urine and cerebrospinal fluid patients with multiple
sclerosis (31)(32).
One potential drawback of quantitative FLC assays is that they cannot
directly determine clonality, although altered : ratios are
highly suggestive of clonality, particularly if extreme. On the other
hand, ratios might be normal in early disease or during clinical
remission, and increased polyclonal FLC concentrations will mask low
concentrations of monoclonal FLCs. In addition, biclonal gammopathies
of different FLC types could produce normal : ratios although the
concentrations of both molecules might be increased. In all of these
situations, clonality must be confirmed by electrophoresis. In
spite of these limitations, the potential benefits of simple FLC
immunoassays for assessing monoclonal gammopathies, in terms of
improved sensitivity, accuracy, cost savings, and the use of serum as a
test medium, are considerable.
In conclusion, previously published immunoassays for FLCs have had little clinical impact either because the techniques were too complex or because the antibodies were nonspecific. The automated, turbidimetric immunoassays described here may allow serum and urine samples to be readily assessed for FLC concentrations in a routine, clinical laboratory setting.
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Acknowledgments |
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Footnotes |
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References |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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chains in human serum and urine using pairs of monoclonal antibodies reacting with C epitopes not available on whole immunoglobulins. Clin Exp Immunol 1983;52:234-240.[Web of Science][Medline]
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and chains in serum and the significance of their ratio in patients with multiple myeloma. Br J Haematol 1992;81:223-230.[Web of Science][Medline]
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:) ratios of serum and urinary free light chains. Clin Exp Immunol 1998;111:457-462.[Web of Science][Medline]
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and -immunoreactivity, orosomucoid and 
1-antitrypsin in urine stored at -20 °C. Scand J Urol Nephrol 1997;31:67-71.[Web of Science][Medline]
[Order article via Infotrieve]
light chains in patients with diabetes mellitus. Kidney Int 1990;37:1120-1125.[Web of Science][Medline]
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M. A. Dawson, S. Patil, and A. Spencer Extramedullary relapse of multiple myeloma associated with a shift in secretion from intact immunoglobulin to light chains Haematologica, January 1, 2007; 92(1): 143 - 144. [Abstract] [Full Text] [PDF]
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 J-E Gottenberg, F Aucouturier, J Goetz, C Sordet, I Jahn, M Busson, J-M Cayuela, J Sibilia, and X Mariette Serum immunoglobulin free light chain assessment in rheumatoid arthritis and primary Sjogren's syndrome Ann Rheum Dis, January 1, 2007; 66(1): 23 - 27. [Abstract] [Full Text] [PDF]
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 J. A. Katzmann, A. Dispenzieri, R. A. Kyle, M. R. Snyder, M. F. Plevak, D. R. Larson, R. S. Abraham, J. A. Lust, L. J. Melton III, and S. V. Rajkumar Elimination of the Need for Urine Studies in the Screening Algorithm for Monoclonal Gammopathies by Using Serum Immunofixation and Free Light Chain Assays Mayo Clin. Proc., December 1, 2006; 81(12): 1575 - 1578. [Abstract] [Full Text] [PDF]
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M. Drayson, G. Begum, S. Basu, S. Makkuni, J. Dunn, N. Barth, and J. A. Child Effects of paraprotein heavy and light chain types and free light chain load on survival in myeloma: an analysis of patients receiving conventional-dose chemotherapy in Medical Research Council UK multiple myeloma trials Blood, September 15, 2006; 108(6): 2013 - 2019. [Abstract] [Full Text] [PDF]
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J. A. Katzmann Serum Free Light Chain Specificity and Sensitivity: A Reality Check Clin. Chem., September 1, 2006; 52(9): 1638 - 1639. [Full Text] [PDF]
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P. G. Hill, J. M. Forsyth, B. Rai, and S. Mayne Serum Free Light Chains: An Alternative to the Urine Bence Jones Proteins Screening Test for Monoclonal Gammopathies Clin. Chem., September 1, 2006; 52(9): 1743 - 1748. [Abstract] [Full Text] [PDF]
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 A. M. S. Muller, A. Geibel, H. P. H. Neumann, A. Kuhnemund, A. Schmitt-Graff, J. Bohm, and M. Engelhardt Primary (AL) Amyloidosis in Plasma Cell Disorders Oncologist, July 1, 2006; 11(7): 824 - 830. [Abstract] [Full Text] [PDF]
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G. Palladini, F. Lavatelli, P. Russo, S. Perlini, V. Perfetti, T. Bosoni, L. Obici, A. R. Bradwell, G. M. D'Eril, R. Fogari, et al. Circulating amyloidogenic free light chains and serum N-terminal natriuretic peptide type B decrease simultaneously in association with improvement of survival in AL Blood, May 15, 2006; 107(10): 3854 - 3858. [Abstract] [Full Text] [PDF]
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A. Dispenzieri, M. Q. Lacy, J. A. Katzmann, S. V. Rajkumar, R. S. Abraham, S. R. Hayman, S. K. Kumar, R. Clark, R. A. Kyle, M. R. Litzow, et al. Absolute values of immunoglobulin free light chains are prognostic in patients with primary systemic amyloidosis undergoing peripheral blood stem cell transplantation Blood, April 15, 2006; 107(8): 3378 - 3383. [Abstract] [Full Text] [PDF]
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D. Sviridov, B. Meilinger, S. K. Drake, G. T. Hoehn, and G. L. Hortin Coelution of Other Proteins with Albumin during Size-Exclusion HPLC: Implications for Analysis of Urinary Albumin Clin. Chem., March 1, 2006; 52(3): 389 - 397. [Abstract] [Full Text] [PDF]
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 T. D. Jaskowski, C. M. Litwin, and H. R. Hill Detection of {kappa} and {lambda} Light Chain Monoclonal Proteins in Human Serum: Automated Immunoassay versus Immunofixation Electrophoresis Clin. Vaccine Immunol., February 1, 2006; 13(2): 277 - 280. [Abstract] [Full Text] [PDF]
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 M. R. Nowrousian, D. Brandhorst, C. Sammet, M. Kellert, R. Daniels, P. Schuett, M. Poser, S. Mueller, P. Ebeling, A. Welt, et al. Serum Free Light Chain Analysis and Urine Immunofixation Electrophoresis in Patients with Multiple Myeloma Clin. Cancer Res., December 15, 2005; 11(24): 8706 - 8714. [Abstract] [Full Text] [PDF]
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 M. Q. Lacy, W. J. Hogan, M. A. Gertz, A. Dispenzieri, S. V. Rajkumar, S. Hayman, S. Kumar, M. R. Litzow, and A. L. Schroeter Successful Treatment of Scleromyxedema With Autologous Peripheral Blood Stem Cell Transplantation Arch Dermatol, October 1, 2005; 141(10): 1277 - 1282. [Abstract] [Full Text] [PDF]
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I. Brockhurst, K. P. G. Harris, and C. S. Chapman Diagnosis and monitoring a case of light-chain deposition disease in the kidney using a new, sensitive immunoassay Nephrol. Dial. Transplant., June 1, 2005; 20(6): 1251 - 1253. [Abstract] [Full Text] [PDF]
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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. A. Katzmann, R. S. Abraham, A. Dispenzieri, J. A. Lust, and R. A. Kyle Diagnostic Performance of Quantitative {kappa} and {lambda} Free Light Chain Assays in Clinical Practice Clin. Chem., May 1, 2005; 51(5): 878 - 881. [Abstract] [Full Text] [PDF]
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G. Palladini, V. Perfetti, S. Perlini, L. Obici, F. Lavatelli, R. Caccialanza, R. Invernizzi, B. Comotti, and G. Merlini The combination of thalidomide and intermediate-dose dexamethasone is an effective but toxic treatment for patients with primary amyloidosis (AL) Blood, April 1, 2005; 105(7): 2949 - 2951. [Abstract] [Full Text] [PDF]
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C. Fischer, B. Arneth, J. Koehler, J. Lotz, and K. J. Lackner Kappa Free Light Chains in Cerebrospinal Fluid as Markers of Intrathecal Immunoglobulin Synthesis Clin. Chem., October 1, 2004; 50(10): 1809 - 1813. [Abstract] [Full Text] [PDF]
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G. P. Mead, M. T. Drayson, H. D. Carr-Smith, and A. R. Bradwell Measurement of Immunoglobulin Free Light Chains in Serum Clin. Chem., November 1, 2003; 49(11): 1957 - 1958. [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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M. Salomo, P. Gimsing, and L. B. Nielsen Simple Method for Quantification of Bence Jones Proteins Clin. Chem., December 1, 2002; 48(12): 2202 - 2207. [Abstract] [Full Text] [PDF]
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J. A. Katzmann, R. J. Clark, R. S. Abraham, S. Bryant, J. F. Lymp, A. R. Bradwell, and R. A. Kyle Serum Reference Intervals and Diagnostic Ranges for Free {kappa} and Free {lambda} Immunoglobulin Light Chains: Relative Sensitivity for Detection of Monoclonal Light Chains Clin. Chem., September 1, 2002; 48(9): 1437 - 1444. [Abstract] [Full Text] [PDF]
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A. Goldammer, K. Derfler, K. Herkner, A. R. Bradwell, W. H. Horl, and M. Haas Influence of plasma immunoglobulin level on antibody synthesis Blood, June 17, 2002; 100(1): 353 - 355. [Abstract] [Full Text] [PDF]
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R. L. Comenzo and M. A. Gertz Autologous stem cell transplantation for primary systemic amyloidosis Blood, May 29, 2002; 99(12): 4276 - 4282. [Abstract] [Full Text] [PDF]
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R. S. Abraham, R. J. Clark, S. C. Bryant, J. F. Lymp, T. Larson, R. A. Kyle, and J. A. Katzmann Correlation of Serum Immunoglobulin Free Light Chain Quantification with Urinary Bence Jones Protein in Light Chain Myeloma Clin. Chem., April 1, 2002; 48(4): 655 - 657. [Full Text] [PDF]
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M. S. Graziani, G. Merlini, A. R. Bradwell, M. T. Drayson, and G. P. Mead Measurement of Free Light Chains in Urine Drs. Bradwell, Drayson, and Mead respond: Clin. Chem., November 1, 2001; 47(11): 2069 - 2070. [Full Text] [PDF]
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), IgM
), IgM
), triglycerides (5.95 g/L; 
), and hemoglobin (3 g/L; 
).
Data points are means; bars, 95% confidence
intervals.
).