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CORRESPONDENCE
CD7 EXPRESSION IN ACUTE MYELOID LEUKEMIA
To the Editor:
The significanceof CD7 expressionin acute myelocyticleukemia
(AML) has been discussed by Kita et al’ in a recent issue. We would
like to contribute with our experience in 154 previously untreated
AML patients observed between January 1987 and June 1992, median age 57 years. For remission induction, all patients received a
combination of cytosine arabinosideand an anthracycline(patients
<60 years) or mitoxantrone (patients >60 years). Immunophenotype studieswere performed on bone marrow blast cells using combinations of phycoerythrin (PE) and fluorescein isothyocyanate
(F1TC)-conjugated monoclonal antibodies (MoAbs). Blast cells
were selected on the basis of forward light scatter gating and a panmyeloid marker, either CD13 or CD33. An IgGh MoAb antLCD7
(Leu-9 FITC; Becton Dickinson, Mountain View, CA) was used. A
positive reaction was considered when 20% or more of the gated
cells expressed CD7 antigen. Fluorescence quantitative evaluation
was performed by using an Epics Profile I cytometer (Coulter, Hialeah, FL). Interestingly, a review of one-parameter flow cytometry
histograms showed that the CD7 fluorescenceintensity was low or
intermediate. Results of incidence of CD7 positivity in each
French-American-British (FAB) classificationcategory are detailed
in Table 1. CD7 was positive in 49 cases (31.8%), being mainly
expressed in the FAB MO and M5 groups and significantly correlated with CD34 (P < .001), HLA-DR (P = .018), white blood cell
(WBC) count greater than 50 X 109/L (P = .038). The different
percentage of positivity between the two studies might be related to
the use of different anti-CD7 antibody isotypes. Fifteen cases of
CD7+ simultaneously expressed TdT, but no case CD7+TdT+
showed cCD3. Besides, we found no correlation between CD7 positivity and hepatomegaly and/or central nervous system involvement. The complete remission (CR) rate was significantlylower in
CD7+ patients (39% v 67%, P = .032). These cases also showed
shorter survival (P < ,001) and decreased continuous complete remission (CCR) (P < .OO I ) (Fig 1, A and B). Moreover, in our series
of patients, CD7+ cases with both CD2+ and TdT+ AML had a
lower overall and disease-free survival than CD7- cases. We identified a phenotypic group with particular bad prognosis, the
[CD7+CD14+](14.9%), selectively expressed in FAB M4 and M5
subtypes ( P< .OO 1 ). They responded poorly to standard chemotherapy for AML (CR rate: 32%) and had an unfavorable outcome
(median survival: 16 f 2.8 weeks). Multivariate life-table analysis
on several variables including age, WBC count, CD7, CD2, CD19,
HLADR, CD34, and CD I4 confirmed the prognostic value of CD7
Table 1. Incidence of CD7+ Cases in FAB Classes
FAB Group
MO
M1
M2
M3
M4
M5
Total
CO7 EXPRESSION AN0 SURVIVAL
A
No. of CD7+
Cases
Incidence
11
41
40
19
27
16
6
14
12
8
9
54.5
34.1
30
0
29.6
56.2
154
49
31.8
Total Tested
0
Blood, Vol 82, No 9 (November l ) , 1993: pp 2929-2932
(%I
l
n
L-COT-
I
-CD7*
P<0. 001
0.1
0
0
20
40
60
80
100
120
140
160
I
I
180
200
WEEKS
CO7 E X P R E S S I O N AND CCR
B
l
n
0.8
P
k
0.7
0
I
L 0.4
I
T 0.3
Y
.
!--
0.2j
0.1
1
01
0
l11=19
I
I
20
40
60
80
I
,
100 120
WEEKS
I
140
160
180
200
Fig 1. (A) CD7 expression at the time of diagnosis significantly
affected survival duration. (B) CD7- cases had a much longer CCR
than CD7+ cases.
both with regard to survival (P = .001) and CCR duration (P =
.018). In conclusion, as observed by Kita and other investigator^,"^
CD7 positivity can be considered to be a phenotypicalrisk factor for
AML, and such an expression could identify a different clinical
entity of AML.
Giovanni Del Poeta
Roberto Stasi
Adriano Venditti
Mario Masi
Giuseppe Papa
Cattedra e Divisione di Ematologia
Universitb “Tor Vergata
Ospedale S. Eugenio
Rome, Italy
”
2929
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2930
CORRESPONDENCE
REFERENCES
1. Kita K, Miwa H, Nakase K, Kawakami K, Kobayashi T, Shirakawa S, Tanaka I, Ohta C, Tsutani H, Oguma S, Kyo T, Dohy H,
Kamada N, Nasu K, Uchino H (The Japan Cooperative Group of
Leukemia/Lymphoma): Clinical importance of CD7 expression in
acute myelocytic leukemia. Blood 81:2399, 1993
2. Schwarzinger I, Valent P, Koller U, Marosi C, Schneider B,
Haars 0, Knapp W, Lechner K, Bettleheim P: Prognostic significance of surface marker expression on blasts of patients with de
novo acute myeloblastic leukemia. J Clin Oncol 8:423, 1990
3. Osada H, Emi N, Ueda R, Set0 M, Koike K, Suchi T, Kojima
S, Obata Y, Takahashi T: Genuine CD7 expression in acute leukemia and lymphoblastic lymphoma. Leuk Res 14:869, 1990
4. Ball ED, Davis RB, Griffin JD, Mayer RJ, Davey FR, Arthur
DC, Wurster-Hill D, Noll W, Elghetany T, Allen SL, Rai K, Lee EJ,
Schiffer CA, Bloomfield CD: Prognostic value of lymphocyte surface markers in acute myeloid leukemia. Blood 77:2242, 1991
5 . Yumura-Yagi K, Hara .I,
Kurahashi H, Okamura J, Koizumi
S, Toyoda Y, Murayama N, lnoue M, Ishihara S, Tawa A, Nishiura
T, Kaneyama Y , Okada S, Kawa-Ha K: Clinical significance of
CD7-positive stem cell leukemia. Cancer 68:2273, 199t
From www.bloodjournal.org by guest on February 6, 2015. For personal use only.
1993 82: 2929-2930
CD7 expression in acute myeloid leukemia [letter; comment] [see
comments]
G Del Poeta, R Stasi, A Venditti, M Masi and G Papa
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