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H Miwa, K Kita, K Nishii, N Morita, N Takakura, K Ohishi, N Mahmud, S Kageyama, M Fukumoto and S Shirakawa
Second Department of Internal Medicine, Mie University School of Medicine,
Tsu, Japan.
MDR1 gene expression was examined in acute leukemia cells from 75 Japanese
patients at diagnosis (50 with acute myeloblastic leukemia [AML]: 10 M1, 18
M2, 5 M3, 8 M4, 9 M5; 25 with acute lymphoblastic leukemia [ALL]: 13
B-precursor, 12 T-lineage). The results of MDR1 mRNA expression by reverse
transcriptase polymerase chain reaction were confirmed by immunostaining
using the anti-P-glycoprotein monoclonal antibody UIC2 and by a functional
study using the rhodamine efflux test. Morphologically, AML M1 cases had
the highest incidence of MDR1 gene expression (6 of 10 patients).
Phenotypically, CD7 and CD34 were the only surface markers that were
significantly associated with MDR1 gene expression (P < .01). In
CD7+CD4-CD8- ALL, which is thought to originate from the
lymphohematopoietic stem cell, expressed the MDR1 gene with a high
incidence (six of eight patients), whereas three surface CD3+ and one
CD4+CD8+ T-cell ALL (T-ALL) did not have detectable MDR1 transcripts. Only
two cases of 13 B-precursor ALL had MDR1 mRNA, one of which had the
Philadelphia (Ph1) chromosome. No association was observed between MDR1
gene expression and CD34 positivity in ALL. Our results that MDR1 mRNA was
frequently expressed in CD7+ AML and CD7+CD4-CD8- ALL, together with the
previous reports indicating clinical similarities between these leukemias,
provides a clue to clarify a relationship between CD7+ AML and CD7+CD4-CD8-
ALL. In addition, MDR1 expression in CD7+ AML/ALL might be responsible for
the poor response to conventional chemotherapies of these types of
leukemia.
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| Copyright © 1993 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||