Blood, Vol. 94 No. 11 (December 1), 1999:
pp. 3954-3956
CORRESPONDENCE
Tenupodia Formation by Blasts in Bone Marrow Aspirate
Smears From a Patient With Acute Monoblastic Leukemia
 |
LETTER |
To the Editor:
Primitive hematopoietic myeloid cells have been observed to extend
long, thin pseudopodia. Recently, Francis et al1 reported the presence of 2 new morphologic types of pseudopodia, tenupodia and
magnupodia, formed by the human myeloid progenitor cell line KG1a and
human CD34+ cells from fetal liver, umbilical cord blood,
adult bone marrow, and mobilized (using either granulocyte-macrophage
colony-stimulating factor [GM-CSF] or G-CSF) peripheral blood.
Tenupodia are thin, linear segments that bifurcate multiple times.
Magnupodia are thicker, longer, flexible dynamic segments that
both extend and retract. Francis et al1 suggested that
tenupods and magnupods play both sensory and mechanical roles
during migration and homing of hematopoietic stem cells.
The human CD34+ cells displaying tenupods and magnupods
reported by Francis et al1 were isolated after several
purification steps including immunomagnetic separation column, flow
cytometric sorting, cell culture, and cryopreservation. Francis et
al1 did not assess for the presence of tenupodia and
magnupodia formation by blasts in bone marrow aspirate smears from
patients with acute myeloid leukemia. This case is reported to
illustrate blasts forming tenupods in bone marrow aspirate smears of a
patient with acute monoblastic leukemia.
A 7-month-old Hispanic girl was admitted to M.D. Anderson Cancer Center
on November 22, 1998 with a 2-week history of erythematous sclera
followed by proptosis of the right eye. The previous medical history
was unremarkable. Her developmental milestones were within normal
limits. Physical examination revealed temperature 36.4°F, pulse 126 beats/min, respiratory rate 26 breaths/min, blood pressure 119/71 mm
Hg, weight 8.5 kg, and height 43 cm. The right eye showed mild
proptosis and a dilated pupil, unresponsive to light. Fundoscopy exam
demonstrated a yellow retina. The left eye was normal. There were no
skin lesions or visceromegaly. Complete blood count (CBC) revealed
hemoglobin 6.4 g/dL, platelet count 14,000/µL, and white blood cell
count 5,500/µL. The peripheral blood smear differential count was:
11% neutrophils, 84% lymphocytes, 3% monocytes, 1% eosinophils, and
1% basophils. The serum lactate dehydrogenase (LDH) was 1,222 U/L
(normal, 118 to 273 U/L). She required transfusions of platelets and
red blood cells. Computed tomographic (CT) scan showed diffuse
opacification of the retrobulbar tissue with no bone destruction.
Biopsy specimens of the retrobulbar tissue showed mature adipose tissue
and fibrosis with no evidence of malignancy. Bone marrow aspiration was
done on November 26, 1998 and smears showed 11% blasts, orderly
granulopoiesis and erythropoiesis, and megakaryocytic hypoplasia. The
blasts extended long, thin pseudopodia that originated from a common
site on the cell surface with branches at some distance away from the
cell body (Fig 1). Cytochemical studies
showed that the blasts were negative for myeloperoxidase, terminal
deoxynucleotidyl transferase (TdT), Periodic Acid-Schiff (PAS)
reaction, and butyrate esterase. Flow cytometry immunophenotypic
studies showed that the blasts were positive for CD33, CD34, CD45, and
CD117 demonstrating immature myeloid lineage. Cytogenetic study showed
a normal 46, XX karyotype.
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| Fig 1.
Blast-forming tenupods in bone marrow aspirate smear of a
patient with acute monoblastic leukemia.
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Subsequently, bone marrow aspiration and biopsy were performed on
December 20, 1998. The aspiration yielded a dry tap, but bone marrow
biopsy touch imprints demonstrated 98% blasts. The bone marrow biopsy
specimen was hypercellular, greater than 90%, and the architecture was
effaced by large infiltrating cells with distinct nucleoli.
Cytochemical studies showed that the blasts were positive for butyrate
esterase and negative for myeloperoxidase and TdT. Immunohistochemical
studies performed using fixed, paraffin-embedded tissue sections
showed that the neoplastic cells strongly expressed CD45 and CD68.
In aggregate, these findings established the diagnosis of acute
monoblastic leukemia (M5 using the French-American-British classification).2
We observed blasts deploying tenupodia in the bone marrow aspirate
smears in the early phase of this patient's acute myeloid leukemia.
The lack of adequate bone marrow aspiration smears may explain our
inability to identify these tenupodia later in the patient's clinical
course, when the acute leukemia was florid. Tenupodia formation by
leukemic monoblasts in the bone marrow suggests that tenupodia are
somehow involved in replacement of the bone marrow space. These
tenupodia may be involved in the interaction between blasts and the
bone marrow microenvironment, which probably also involves adhesion
molecules such as fibronectin, integrin 
5
1, vinculin, and
actin.3 Tenupodia may play a role in cell-to-cell
interaction. According to Francis et al,1 tenupods adhere
to substrate and can bifurcate multiple times to connect to the
membranes of cells up to 330 µmol/L apart. Tenupodia may also be
involved in migration, as migration requires the cell to deform,
extending cytoplasmic projections and generating contractile forces as it moves.
Carlos Bueso-Ramos
L. Jeffrey Medeiros
Division of Pathology and Laboratory Medicine
The
University of Texas, M.D. Anderson Cancer Center
Houston,
TX
Theodore Zipf
Cesar Nunez
David Tubergen
Division of Pediatrics
University of Texas, M.D.
Anderson Cancer Center
Houston, TX
| |
REFERENCES |
1.
Francis K, Ramakrishna R, Holloway W, Palsson BO:
Two new pseudopod morphologies displayed by the human hematopoietic KG1a progenitor cell line and by primary human CD34+ cells.
Blood
92:3616, 1998[Abstract/Free Full Text]
2.
Bennet JM, Catosvsky D, Daniel MT, Flandrin G, Galton DAG, Gralnick HR, Sultan C:
Proposed revised criteria for the classification of acute myeloid leukemia. A report of the French-American-British cooperative group.
Ann Intern Med
103:620, 1985
3.
Asano T, Fukuda Y, Katsube Y, Fukunaga Y, Sugisaki Y, Yamanaka N, Yamamoto M:
Infantile acute monocytic leukemia with tumor formation in the skin expressing adhesion molecules as seen by electron microscopy.
Leuk Lymphoma
23:173, 1996[Medline]
[Order article via Infotrieve]
Response
To the Editor:
This recent report by Bueso-Ramos1 describes the presence
of tenupodia in bone marrow aspirate smears. Our original description of tenupodia focused on CD34+ cells and the
CD34+ cell line KG1a.2 The observation of
extension of tenupodia by blast cells reported by Bueso-Ramos et al are
in agreement with our findings, and provide an independent verification
of tenupodia extension by hematopoietic cells.
We have now observed these podia in mixed cell cultures and our
research has shown that other cell phenotypes extend tenupodia. In Fig
1, primitive hematopoietic KG1a cells
(red
PKH26 stained) were cocultured with fibroblastic HT1080 cells
(greenPKH2 stained) to simulate the heterogeneous cellularity of the
bone marrow microenvironment. We found that the KG1a cells form
connections with the HT1080 cells via red tenupodia (shown in Fig 1).
Additionally, tenupodia that originated from the HT1080 cells and
connected with the KG1a cells appeared green (not shown). These
observations provide evidence that suggests tenupodia are involved in
heterogeneous inter-cellular interactions.
Although we have yet to elucidate the function of these tenupodia
mediated inter-cellular interactions, we are continuing to investigate
other aspects of tenupodia and magnupodia formation. Using
immunohistochemical staining, we have cataloged the various surface
markers and adhesion molecules that appear on these podia.3 We have also succeeded in transiently transfecting KG1a cells with an
actin-green fluorescent protein construct. Confocal images of these
cells revealed that actin is indeed present in magnupodia. These
studies show that the podia contain molecular components that one would
expect to find in and on the surface of these podia. However, their in
vivo physiological role remains uncertain. The podia can possibly play
a role in navigation and migration, long distance cell-cell
interaction, or even in controlled cell death processes. Further
investigation is required to determine their physiological function.
Karl Francis
Duk Jae Oh
Alex Martinez
Bernhard Palsson
Department of Bioengineering
University of California
San Diego
La Jolla, CA
| |
REFERENCES |
1.
Bueso-Ramos C, Medeiros LJ, Zipf T, Nunez C, Tubergen D:
Tenupodia formation by blasts in bone marrow aspirate smears from a patient with acute monoblastic leukemia.
Blood
94:3954, 1999[Free Full Text]
2.
Francis K, Ramakrishna R, Holloway W, Palsson BO:
Two new pseudopod morphologies displayed by the human hematopoietic KG1a progenitor cell line and by primary human CD34+ cells.
Blood
92:3616, 1998
3.
Holloway W, Martinez A, Oh DJ, Francis K, Rama-krishna R, Palsson B:
Key adhesion molecules are present on long podia extended by hematopoietic cells.
Cytometry
37:171, 1999[Medline]
[Order article via Infotrieve]
