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Blood, 1 October 2001, Vol. 98, No. 7, pp. 2200-2209
NEOPLASIA
Expression of mast cell tryptase by myeloblasts in a group of
patients with acute myeloid leukemia
Wolfgang R. Sperr,
John-Hendrik Jordan,
Mehrdad Baghestanian,
Hans-Peter Kiener,
Puchit Samorapoompichit,
Hans Semper,
Alexander Hauswirth,
Gerit-Holger Schernthaner,
Andreas Chott,
Susanne Natter,
Dietrich Kraft,
Rudolf Valenta,
Lawrence B. Schwartz,
Klaus Geissler,
Klaus Lechner, and
Peter Valent
From the Department of Internal Medicine I, Division of
Hematology and Hemostaseology, Department of Internal Medicine III,
Division of Rheumatology, Institute of Histology and Embryology,
Department of Clinical Pathology, and Institute of Pathophysiology,
University of Vienna, Austria; Department of Internal Medicine,
Division of Rheumatology, Allergy and Immunology, Virginia Commonwealth
University, Richmond, VA.
 - and  -tryptase genes encode serine
proteases that are abundantly expressed by mast cells. Under
physiologic conditions other myeloid cells are virtually tryptase
negative. However, tryptases are also expressed in several myeloid
leukemia cell lines. In this study, serum total tryptase levels were
determined in 150 patients with acute leukemias (de novo acute myeloid
leukemia [AML], n = 108; secondary AML, n = 25; acute lymphoid
leukemia [ALL], n = 17) by fluoroenzyme immunoassay. In
healthy subjects (n = 30), tryptase levels ranged between 2.0 and 12.6 ng/mL. Elevated tryptase levels (> 15) were detected in 42 (39%) of 108 patients with de novo AML and in 11 (44%) of 25 patients
with secondary AML. No elevated tryptase levels were found in patients
with ALL. In de novo AML, elevated tryptase levels were frequently
detected in patients with French-American-British classification M0 (6 of 9), M2 (9 of 14), M3 (4 of 6), and M4eo (7 of 7), and less frequently in M1 (7 of 20), M4 (6 of 26), M5 (2 of 18), M6 (0 of 5), or
M7 (1 of 3). The highest tryptase levels were found in M4eo.
Immunohistochemical staining of bone marrow sections with anti-tryptase
antibody as well as immunoelectron microscopy revealed tryptase
expression in the cytoplasm of myeloblasts. As assessed by Northern
blotting and reverse transcriptase-polymerase chain reaction, AML
cells expressed -tryptase messenger RNA (mRNA) but little or no
-tryptase mRNA. In AML patients with elevated serum tryptase before
chemotherapy, who entered complete remission, tryptase levels returned
to normal or near normal values. Blast cell persistence or regrowth
was associated with a persistently elevated level or recurrent
increase of tryptase. Together, tryptase is expressed in myeloblasts in
a group of AML and may serve as a useful disease-related marker.
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