International Journal of Myeloma 5(3): 30–35, 2015
©日本骨髄腫学会

ORIGINAL

Clinical and laboratory significance of CD56 (a neural cell adhesion
molecule) positivity in multiple myeloma and AL amyloidosis
Kanji MIYAZAKI1 and Kenshi SUZUKI1
CD56 is frequently expressed by malignant plasma cells in patients with multiple myeloma (MM) or AL amyloidosis(ALA). The aim of this retrospective study was to examine CD56 expression in patients with MM or ALA anddetermine the clinical and laboratory characteristics associated with its expression. Bone marrow samples ofpatients were analyzed by flow cytometry. Various clinical data with regard to the expression or non-expression of
CD56 were compared. In total, 316 patients (215 with MM and 101 with ALA) were included in the study. The CD56
expression rate was higher in patients with MM than that in those with ALA. Patients with MM had a median CD56
expression rate of 96.4%, and serum total protein levels were significantly higher in the CD56+ group (p < 0.001).
Patients with ALA had a median CD56 expression rate of 1.9%, and serum lactate dehydrogenase levels weresignificantly higher in the CD56+ group (p = 0.033). These findings suggest that the CD56 expression rate differs inmonoclonal plasma cells between patients with MM and ALA, and that M-protein secretions are increased inpatients with CD56+ MM.
Key words:

multiple myeloma, AL amyloidosis, CD56, NCAM

CD56 is expressed in approximately 50% of ALA cases 3). In

Introduction

patients with ALA, the number of neoplastic plasma cells is
CD56 (a neural cell adhesion molecule, NCAM) is a mem-

usually lesser and light chain restriction is less reliable because

brane glycoprotein belonging to the immunoglobulin super-

the normal plasma cells are not suppressed. CD56 expression

1)

family . Normal plasma cells do not express CD56, but it is fre-is helpful in identifying neoplastic plasma cells in ALA. Unlike

quently expressed by malignant plasma cells in patients with

MM, the clinicopathological correlation between CD56 expres-2,3). CD56 ission and ALA remains poorly understood. By flow cytometry,

expressed in approximately 65% of MM cases and may bea small number of neoplastic plasma cells from patients with­associated with osteolysis, good prognosis. CD56 negativity

ALA can be analyzed rapidly 5).

multiple myeloma (MM) or AL amyloidosis (ALA)

may be associated with poor prognosis, extramedullary in-

The difference in CD56 expression rates between MM andvolvement, plasmablastic morphology, plasma cell leukemic

ALA suggests differences in the pathogenesis of these dis-state, and non-hyperdiploidy chromosomal abnormality.

eases, but to the best of our knowledge, such a study has not­However, these findings have been questioned, and a pre­yet been reported. The aim of this retrospective study was tovious prospective study reported that patients with CD56− MMexamine CD56 expression in patients with MM and ALA bypresented a lower frequency of osteolysis, while they were

flow cytometry in order to define the clinical characteristics

not associated with a poor prognosis 4).

associated with CD56 expression.

Materials and Methods
Received: September 1, 2014, accepted: December 30, 2014
1
Department of Hematology, Japanese Red Cross Medical Center
Corresponding author: Kanji MIYAZAKI
Department of Hematology, Japanese Red Cross Medical Center,
Tokyo, Japan, 4-1-22 Hiroo, Shibuya-ku, Tokyo 150-8935, Japan
TEL: 81-3-3400-1311
E-mail: miyazaki_kanji@med.jrc.or.jp

30

International Journal of Myeloma

vol. 5 no. 3 (2015)

Patients
This retrospective study included 215 patients with MM and101 patients with ALA who underwent bone marrow examination at the Department of Hematology of the Japanese Red
Cross Medical Center in Tokyo, Japan, from May 2006 to
December 2012.

CD56 positivity in MM and ALA

The diagnosis of MM or ALA was obtained from the hospital
medical records. Various clinical and laboratory data, including
age; sex; bone marrow examination; monoclonal typing;
serum concentrations of immunoglobulins, total protein,
albumin, calcium, lactate dehydrogenase, uric acid, and­beta-2 microglobulin at the bone marrow examination; andthe clinical course were also obtained from the hospital­medical records. These data were compared with regard to
CD56 expression. Approval was obtained from the Institutional Review Board of the Japanese Red Cross Medical Center,
Tokyo, Japan, exempting the study from requiring consent
from individual patient’s consent.
Flow cytometry
Bone marrow aspirate samples were analyzed using a flow
cytometer (FACSCalibur, Becton Dickinson and Company,
Tokyo, Japan). The following antibodies were used for flow
cytometry: CD38 (Becton Dickinson and Company, Tokyo,
Japan), CD138 (Beckman Coulter, Tokyo, Japan), CD56 (Becton
Dickinson and Company, Tokyo, Japan), and CD19 (Beckman
Coulter, Tokyo, Japan). Twenty thousand cells were analyzed toTable 1.

Characteristics of patients with multiple myeloma

Multiple myeloma (n = 215)
GenderMale
Female95120

Age (years)
Median
Range

65
29–88

Monoclonal protein
IgG kappa
IgG lambda
IgA kappa
IgA lambda
IgD kappa
IgD lambda
BJ kappa
BJ lambda
Non-secretory
Not available
Percentage of CD38+ plasma cells (%)
Median
Range

75
44
25
11
2
2
19
12
1
24
13.6
0.1–87.0

determine the percentage of bone marrow cells.
Plasma cells were identified by gating using CD38. Next
the gate was set for plasma cells and the expression levels of
CD56, CD19, and CD138 were analyzed. The percentage ofplasma cells expressing CD56 was evaluated by flow cytometry. Patients were considered to be positive for CD56 when its
expression was detected in more than 50% of tested plasma
cells.
Statistical analysis
Clinical data were evaluated with regard to CD56 expression
using the Shapiro–Wilk test, Levene’s test, Student’s t-test, orMann–Whitney test. Survival analysis was performed by the
Kaplan–Meier method, and comparisons of survival rates were
evaluated by the log-rank test. A p-value of <0.05 was con­sidered statistically significant. All statistical analyses were­performed using SPSS v.18.0 (IBM Corp., Armonk, NY, USA).

Results
The characteristics of the 316 patients are shown in Tables 1
and 2. The median ages of patients with MM and ALA were 65
years and 64 years, respectively. The information of the type ofTable 2.

Characteristics of patients with AL amyloidosis

AL amyloidosis (n = 101)
GenderMale
Female5645

Age (years)
Median
Range

64
39–84

Monoclonal protein
IgG kappa
IgG lambda
IgA kappa
IgA lambda
IgM kappa
IgM lambda
Biclonal
IgG kappa and IgA kappa
BJ kappa
BJ lambda
Not determined
Percentage of CD38+ plasma cells (%)
Median
Range

3
24
2
9
2
2
1
1
8
22
28
1.9
0.1–23.1

M-protein type was available in 88% in patients with MM and
72% of the patients with ALA. By flow cytometry, the median2, respectively.

ratio of CD38+ plasma cells in bone marrow nucleated cells

CD56+ plasma cells were observed in 72.6% (155/215) of

were 13.6% (range, 0.1%–87.0%) for MM and 1.9% (range,

patients with MM and in 42.6% (43/101) of patients with ALA

0.1%–23.1%) for ALA. Typical phenotypes of CD38+ plasma(Figs. 1 and 2). Among patients with MM (n = 215), the mediancells in patients with MM and ALA are shown in Figures 1 andratio of CD56+ plasma cells was 96.4% (range, 0%–100%).

International Journal of Myeloma

vol. 5 no. 3 (2015)

31

MIYAZAKI and SUZUKI

Figure 1. Typical phenotype of CD38+ plasma cells of a patient with multiple myeloma. A few CD19+ normal plasma cells were present. Most
cells were CD56+ abnormal plasma cells.

Figure 2. The typical phenotype of CD38+ plasma cells of a patient with AL amyloidosis. A few CD19+ normal plasma cells were present. Most
cells were CD56+ abnormal plasma cells. CD20 expression also was observed.

32

International Journal of Myeloma

vol. 5 no. 3 (2015)

CD56 positivity in MM and ALA

Table 3.

Comparison of disease characteristics between patients with CD56+ and CD56− multiple myeloma
CD56+ cases(n = 155)

CD56− cases(n = 60)

GenderMale
Female

68
87

27
33

0.081

Age (years)
Median
Range

65.0
31–88

64.5
29–88

0.477

Serum total protein (g/dL)
MedianRange

8.4
4.0–15.1

6.7
4.7–13.5<0.001

Serum albumin (g/dL)

3.7
2.0–5.0

3.9
2.2–4.8

0.052

Serum calcium (mg/dL)

9.0
7.2–14.3

8.47
7.2–11.9

0.077

Serum lactate dehydrogenase (IU/L)

187.0
85–3337

199.5
104–4922

0.061

Serum beta 2-microglobulin (mg/L)

3.35
1.0–61.6

2.65
1.1–42.3

0.061

29

15

0.306

Bone fracture at diagnosis

p-value

A comparison of the disease characteristics for patients with
CD56+ and CD56− MM is presented in Table 3. Data for serum
calcium, uric acid, and beta 2-microglobulin were unavailable
for all patients. The serum total protein levels were significantly
higher in the CD56+ group than those in the CD56− group (p< 0.001). Although serum albumin and lactate dehydrogenase
levels were lower and serum calcium and beta 2-microglobulinlevels were higher in the CD56+ group than those in the
CD56− group, these differences were insignificant. In addition,
there were no differences in the uric acid levels between thetwo groups. Bone fractures at the diagnosis of MM wereobserved in 18.7% (29/155) of the CD56+ patients and 25%(15/60) of the CD56− patients. However, this difference wasinsignificant (p = 0.306). The median survival of the 215
patients after diagnosis was 79 months, and those of theCD56+ MM group and CD56− MM group were 79 months and86 months, respectively. The survival of patients in both groups
showed no significant differences (p = 0.809; Fig. 3).
Among patients with ALA (n = 101), the median ratio of

Figure 3. Overall survival after the diagnosis of CD56 positive andnegative patients with multiple myeloma. Median survival inthese patients was 79 months and 86 months, respectively(p = 0.809).

CD56+ cells was 33% (range, 1.2%–99.9%). The CD56−/CD19+
expression rate was 8.4% (range 0%−93.3%).

­levels between these two groups. The percentages of patients

A comparison of the disease characteristics of patients withdiagnosed with heart failure, nephrotic syndrome, carpal tun-

CD56+ and CD56− ALA is presented in Table 4. The data fornel syndrome, and hepatomegaly were 37.2% (16/43), 39.5%

beta 2-microglobulin were not available in some patients with

(17/43), 9.3% (4/43), and 4.7% (2/43), respectively, in the

ALA. Serum lactate dehydrogenase levels were significantly

CD56+ ALA group, and 34.5% (20/58), 41.4% (24/58), 1.7%

higher in the CD56+ group than those in the CD56− group(1/58), and 0%, respectively, in the CD56− ALA group, with no(p = 0.033), whereas no differences were observed in total

significant differences between the groups (p = 0.778, 0.853,­protein, albumin, calcium, uric acid, and beta-2 microglobulin

0.084, and 0.099, respectively). The median survival among

International Journal of Myeloma

vol. 5 no. 3 (2015)

33

MIYAZAKI and SUZUKI

Table 4.

Comparison of disease characteristics between patients with in CD56+ and CD56− AL amyloidosis
CD56+ cases(n = 43)

CD56− cases(n = 58)

GenderMale
Female

19
24

37
21

0.051

Age (years)
Median
Range

63.0
39–76

64.5
39–84

0.247

Serum total protein (g/dL)
MedianRange

5.4
3.5–7.1

5.8
2.9–7.7

0.116

Serum albumin (g/dL)

3.5
1.9–4.4

3.5
1.7–4.9

0.240

Serum calcium (mg/dL)

8.6
7.1–9.9

8.47
7.0–10.7

0.077

Serum lactate dehydrogenase (IU/L)

255.0
109–487

218.0
88–5400.033

Serum beta 2-microglobulin (mg/L)

2.4
0.9–6.8

2.5
0.8–13.9

0.912

Heart failure at diagnosis

16

20

0.778

Nephrotic syndrome at diagnosis

17

24

0.853

Carpal tunnel syndrome at diagnosis

4

1

0.084

Hepatomegaly at diagnosis

2

0

0.099

p-valuepatients in the CD56+ ALA group and CD56− ALA group were
70 months and 118 months, respectively. However, this difference was not statistically significant (p = 0.582; Fig. 4).

Discussion
CD56+ plasma cells were observed in 72.6% of patients with
MM and in 42.6% of patients with ALA. These findings are­consistent with those reported previously 4–8). Abnormal CD56
expression is well described in MM, with many reports demonstrating a correlation with CD56 expression. Because CD56 isan adhesion molecule, CD56 positivity may contribute toplasma cell-to-bone trabecular interactions 9). However, data
regarding plasma cell characteristics in ALA are limited 7). A
previous series of 36 cases reported a CD56 expression rate of
50% based on immunohistochemical analysis 3). To the best of
our knowledge, the present study reports the largest numberof ALA cases (101 cases) to date. Because abnormal plasma

Figure 4. Overall survival after the diagnosis of CD56 positive andnegative patients with AL amyloidosis. Median survival in thesepatients was 70 months and 118 months, respectively (p = 0.582).

cells were examined by the same method for both ALA andMM, the CD56 expression rate was considered lower for ALA

total protein levels than patients with CD56− MM. A highly

than that for MM. The low CD56 expression rate in ALA plasma­significant correlation between CD56 expression and parapro-

cells suggests weak plasma cell-to-bone trabecular interac-tein levels in patients with MM was reported previously 10).

tions.

In the same study, CD56 expression, however, was reportedly

In this study, patients with CD56+ MM had higher serum
34

International Journal of Myeloma

vol. 5 no. 3 (2015)

inversely correlated with serum albumin levels. Although, inCD56 positivity in MM and ALA

the present study, serum albumin levels were lower in patients

Acknowledgmentswith CD56+ MM, the difference was not statistically significant.
M protein secretions may be increased in patients with CD56+

We appreciate the work of the medical and nursing staff at

MM, and the CD56 negativity of ALA plasma cells may be

the Japanese Red Cross Medical Center. We offer special thanks

related to a lower M protein (particularly, heavy chain) secre-

to our patients and their families. The authors would like totion, but these assumptions require further investigation. In a

thank Enago (www.enago.jp) for the English language review.

previous report, patients with CD56− MM were found to havehigher beta-2 microglobulin levels 11), but this was not consis-

Conflict of Interest

tent with our findings.
Variable results regarding bone lesions have beenreported

4,11)

The authors declare that they have no conflicts of interest.

. In our study, bone fractures rather than lyticbone lesions were evaluated, but no significant difference wasReferences

observed. This suggests CD56 expression is not related tobone lesions or bone fractures. Previous studies have reported
that CD56 negativity in MM was associated with poorer outcome 4,11), but other studies and our study did not suggest
these differences. CD56 expression may not be a major determinant of prognosis.
Information regarding the clinicopathological significanceof CD56 in ALA is very limited. In this study, lactate dehydrogenase levels were significantly higher in patients with CD56+
ALA than those in patients with CD56− ALA. This paradox was
observed in MM cases, in which serum lactate dehydrogenase
levels were lower in the CD56+ cases than those in the CD56−
cases (p = 0.061). In previous studies, serum lactate dehydrogenase was not significantly different in MM 4,11). This suggeststhat CD56+ ALA is associated with the destruction of manycells, because lactate dehydrogenase is found in various tissues including heart, blood cells, skeletal muscles, liver, and iselevated when these cells are broken. However, the clinicalsignificance of this difference observed in ALA is questionable
and should be clarified in further studies.
Heart failure at diagnosis of ALA was observed in 37.2%
and 34.5% of CD56+ and CD56− patients, respectively, in ourstudy, with no significant difference between the groups.
Heart failure suggesting the cardiac deposition of amyloid in
ALA patients is strongly associated with poor prognosis. The
survival of ALA patients in this study was much better than
expected 12). This might be due to the relatively low rate of­cardiac involvement. Cardiac involvement was observed inapproximately 60% of patients in a previous study 13). However,the survival rate was not significantly different according toCD56 expression. In addition, the incidence rates of nephrotic
syndrome, carpal tunnel syndrome, and hepatomegaly were
not significantly different with regard to CD56 expression.
These findings suggest that in ALA, CD56 expression is not
related to the “dominant” site of deposition. The limitations of
this study were its retrospective design and the inclusion ofboth treated and untreated patients.

1) Cunningham BA, Hemperly JJ, Murray BA, Prediger EA,
Brackenbury R, Edelman GM. Neural cell adhesion molecule:­structure, immunoglobulin-like domains, cell surface modulation,
and alternative RNA splicing. Science. 1987; 236: 799–806.
2) Van Camp B, Durie BG, Spier C, De Waele M, Van Riet I, Vela E, et al.
Plasma cells in multiple myeloma express a natural killer cellassociated antigen: CD56 (NKH-1; Leu-19). Blood. 1990; 76: 377–
82.
3) Deshmukh M, Elderfield K, Rahemtulla A, Naresh KN. Immunophenotype of neoplastic plasma cells in AL amyloidosis. J Clin
Pathol. 2009; 62: 724–30.
4) Kraj M, Sokołowska U, Kopeć-Szlezak J, Pogłód R, Kruk B, Woźniak J,
et al. Clinicopathological correlates of plasma cell CD56 (NCAM)
expression in multiple myeloma. Leuk Lymphoma. 2008; 49: 298–
305.
5) Matsuda M, Gono T, Shimojima Y, Hoshii Y, Ikeda S. Phenotypic
analysis of plasma cells in bone marrow using flow cytometry in
AL amyloidosis. Amyloid. 2003; 10: 110–6.
6) Robillard N, Wuillème S, Moreau P, Béné MC. Immunophenotype
of normal and myelomatous plasma-cell subsets. Front Immunol.
2014; 5: 137.
7) Kumar S, Kimlinger T, Morice W. Immunophenotyping in multiple
myeloma and related plasma cell disorders. Best Pract Res Clin
Haematol. 2010; 3: 433–51.
8) Chang H, Samiee S, Yi QL. Prognostic relevance of CD56 expression in multiple myeloma a study including 107 cases treatedwith high-dose melphalan-based chemotherapy and autologous
stem cell transplant. Leuk Lymphoma. 2006; 47: 43–7.
9) Kaiser U, Auerbach B, Oldenburg M. The neural cell adhesion­molecule NCAM in multiple myeloma. Leuk Lymphoma. 1996; 20:
389–95.
10) Kaiser U, Oldenburg M, Jaques G, Auerbach B, Havemann K.
­Soluble CD56 (NCAM): a new differential-diagnostic and prognostic marker in multiple myeloma. Ann Hematol. 1996; 73: 121–6.
11) Sahara N, Takeshita A, Shigeno K, Fujisawa S, Takeshita K, Naito K,
et al. Clinicopathological and prognostic characteristics of CD56negative multiple myeloma. Br J Haematol. 2002; 117: 882–5.
12) Kumar S, Dispenzieri A, Lacy MQ, Hayman SR, Buadi FK, Colby C,
et al. Revised prognostic staging system for light chain amyloidosis incorporating cardiac biomarkers and serum free light chain
measurements. J Clin Oncol. 2012; 30: 989–95.
13) Kyle RA, Gertz MA. Primary systemic amyloidosis: clinical and­laboratory features in 474 cases. Semin Hematol. 1995; 32: 45–59.

International Journal of Myeloma

vol. 5 no. 3 (2015)35