Understanding
Serum Free Light Chain Assays
Karen H. van Hoeven, MD
The Binding Site, Inc.
San Diego, CA
Why Understand L b
a Test Result
lts?
· Dibt
Diabetes: blood sugar
· Heart disease: cholesterol and others!
·Myeloma: m-proteins / light chains
Myeloma: A Proliferation of the
Plasma Cellls it
in hB
the Bone Marrow
Normally, Plasma Cells
Produce Antibodies
Lots of different types of
Normal
antibodies
Normal vs Myeloma
Many different types
Normal
of antibodies!
Myeloma
Mainly only one type of
antibody and too many!
Structure and Types of Antibodies
(also called
called Immunoglobulins or Ig)
IgG
IgG L
IgA
IgA L
IgD
IgD L
IgE
IgE L
IgM
· Kappa
Free
IgM
g L
· Lambda
light
chain
· IgG · IgD
· IA
IgA · IE
IgE
· IgM
Intact Ig Myeloma
Light Chain Myeloma
Nonsecretory or Oligosecretory Myeloma: very rare form of myeloma
Laboratory Tests
Tests Used to
Detect M-proteins in Myeloma
· Serum protein electrophoresis (SPEP)
· Urine protein
protein electrophoresis (UPEP)
· Immunofixation (IF)
· Quantitative immunoglobulins
immunoglobulins
· Serum free light chain assays
Serum Free
Free Light
Light Chain Assays
Assays
· Free light chains circulate in the blood at
abnormally high levels in
> 90% of multiple my
pyeloma
> 99% of light chain myeloma
> 60% of "nonsecretory" myeloma
· The Free Light Chain Assays measure the levels
of free kappa and free lambda light chains in the
blood
Normal Ranges for
Serum Free Light Chains
Kappa: 3.319.4 mg/L
Kappa: 0.331.94 mg/dL
Lambda: 5.726.3 mg/L
Lambda: 0.572.63 mg/dL
g
Kappa/lambda ratio:
Kappa/lambda ratio:
0.261.65
0.261.65
Katzmann et al. Clin Chem. 2002;14371444.
Interpreting Free Light Chain Tests
Kappa producing disease:
disease:
Increased kappa, normal or low lambda: ratio increased
Kappa
500
Ratio = 250
Lambda
2
Lambda producing disease:
Increased lambda, normal or low kappa: ratio decreased
Kappa
2
Ratio = 0.004
Lambda
500
Normal SPEP- Densitometry
Albumin
Antibodies
Alb 1 2
SPEP in Myeloma = "M-Spike"
Levels of
of Antibodies
Antibodies
· Level of IgG
· Level of IgA
· Ll
Level f
o I D
g
· Level of kappa light chain
· Level of lambda light chain
Why Measure
Measure M-proteins?
· At initial diagnosis
g
· To monitor response to treatment
· To adjust therapy
therapy
· To monitor for relapse
Monitoring Response to
to Treatment
Treatment
Protein
Half Life
IgG
2025 days
IgA
6 days
Free Kappa
24 hours
Free Lambda
36 hours
IgG Multiple Myeloma
Kappa FLC
Monoclonal IgG
300
70
Treatment
250
60
IgG level after 6 months
50
200
,g/L
entration,
40
G
150
Ig
Conc
mg/L
30
100
C
clonal
L
20
L
o
sF
50
10
Mon
0
0
0
200
400
600
800
1000
1200
1400
Time, days
Kappa level after 6 months
Mead et al. Br J Haematol. 2004;126:34854.
Patient With Kappa Light Chain Myeloma
Mi
Mon titored Wk
Wee l
kly Using Free Lih
Lig t
ht Chi
Chain Testiting
Thalidomide
Dex
Ve
V lcade
e
10000
Radiation
1000
L
mg/
Kappa
100
Kappa,
10
NORMAL RANGE
1
03
04
0
04
04
04
04
04
04
04
004
004
004
004
/2
n-14-03
0/20
25/2
10/2004
24/2004
3/200
Ja
8/1
8/
9/
9/
10/8
/20/2
/11/2
10
11
11/2
Myeloma Manager
ManagerTM
· IMF website:
website: www myeloma
.
o
. rg
org
· A good tool that allows you to
capture laboratory results
results, and
display and print tables and charts
Laboratory Variability
Variability
· Absolute values
values in the serum
serum free light
chain assay can vary from lab to lab
Different equip
qpment
Normal lab to lab variation
· Best to have one lab run all tests ifif
possible
Laboratory Variability
Variability
If a new or different laboratory measures
measures
serum free light chains vs the previous
laboratory:
If possible, run the new sample at the
previous laboratory AND
AND at the new
laboratory
Establish a new baseline free
free light chain level
level
During Therapy
· Effective chemotherapy
chemotherapy causes ALL
plasma cells to stop producing antibodies
· Kappa AND lambda light chains may
decrease
International Uniform Response Criteria in
Myeloma1
Myeloma
·
Stringent CR:
Normal free light chain ratio
ratio
Absence of clonal plasma cells in bone marrow by IHC or immunofixation
·
Complete response (CR)
Serum and urine immunofixation negative
Bone marrow with
with 5% plasma cells
Disappearance of soft tissue plasmacytoma
Normalization of free light chain ratio if unmeasurable with above 2 methods
·
Very good partial response (VGPR)
Immunofixation positive but SPEP negative
or
90% in serum M-protein, and urine M-protein < 100 mg/24 h
·
Partial response (PR)
in serum M-protein by 50% and
in urine M-
M protein by
by 90% or to < 200 mg/24 h and
in plasmacytoma size by 50% (if present)
Non-secretory myeloma: 50% in bone marrow plasma cells
50% in difference between involved and uninvolved free light chain
·
Stable disease:
disease: not meeting criteria
criteria for
for CR, sCR, PR
PR or
or progressive
progressive disease
Durie et al. Leukemia. 2006; ;20:1467-73.
Learn More
More About
About It
IMF Brochure
Follow Your
Your Numbers
· Communicate
· Ask questions
· Understand
· Partner
Serum Immunofixation
Normal
IgG
Abnormal Kidney
Kidney Function?
·Kappa
pp and lambda are removed by the kidneys
· If kidneys are not functioning normally, levels of BOTH
kappa and lambda increase
· Level of one type of light chain is often increased with
active myeloma, but the other light chain may also be
slightly increased if there is
is coexisting
coexisting kidney damage,
infection, or inflammation