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ZB Hu, W Ma, CC Uphoff, K Metge, SM Gignac and HG Drexler
DSM-German Collection of Microorganisms and Cell Cultures, Department of
Human and Animal Cell Cultures, Braunschweig, Germany.
Myeloperoxidase (MPO) is found exclusively in the azurophilic granules
(primary lysosomes) of normal myelomonocytic cells. Cytochemical staining
for MPO activity is used clinically to distinguish myeloid from lymphoid
leukemias. We studied the expression of MPO at the RNA and protein level in
140 continuous human leukemia-lymphoma cell lines using classical
cytochemistry, immunofluorescent staining with a specific monoclonal
antibody, Northern blot analysis, and a reverse transcription-polymerase
chain reaction (RT-PCR) amplification assay. Seventy-eight lymphoid
leukemia, myeloma, and lymphoma cell lines were negative; only 3
pre-B-acute lymphoblastic leukemia (ALL) cell lines were MPO-positive. Two
of these MPO-positive pre-B-ALL cell lines showed a trace expression after
RT-PCR and Southern blotting corresponding to 4% to 6% of the transcripts
found in other positive myeloid cell lines. The third pre-B-ALL cell line
was positive in Northern blots and cytochemical/immunofluorescent staining;
however, only few cells were weakly positive in the latter assay. Although
15 of 59 cell lines assigned to the myeloid, monocytic, megakaryocytic, or
erythroid lineages were MPO-positive in Northern blots, those 15 and 13
additional cell lines showed bands of mRNA after RT-PCR. MPO protein was
detected in all 16 Northern-positive cell lines; on the other hand, there
were 4 cell lines that were protein-positive, but Northern- negative.
Differentiation induced by protein kinase C activators 12-O-
tetradecanoylphorbol 13-acetate and Bryostatin 1 or by all-trans retinoic
acid was associated with a decrease in MPO mRNA in all 7 initially positive
cell lines studied, even leading to the complete absence of transcripts,
but the enzymatic activity of the differentiated cells was only slightly
less than that of unstimulated cells. MPO expression could not be induced
in 10 initially negative cell lines. The half-life of MPO mRNA was found to
be about 6 hours and was not shortened by prior exposure of the cells to
the differentiation- inducing agents. These results confirm that MPO
expression is mainly associated with myelomonocytic cells, but also
underline the notion that MPO cannot be used as an absolutely
lineage-specific marker for the distinction of leukemic cells. MPO can be
used as an excellent parameter to characterize the various stages of normal
and induced differentiation.
This article has been cited by other articles:
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| Copyright © 1993 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
