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F Katz, S Malcolm, B Gibbons, R Tilly, G Lam, ME Robertson, B Czepulkowski and J Chessells
Imperial Cancer Research Fund, London, England.
We have studied the cellular and molecular basis of eight cases of infant
null acute lymphoblastic leukemia (ALL). All eight patients were under 9
months of age and presented with leukocyte counts in excess of 60 X
10(9)/L, organomegaly, and in two cases CNS infiltration. Although seven
cases were morphologically classified as ALL, one patient had both lymphoid
and myeloid features. Phenotypic analysis of leukemic blasts from all
patients showed a typical null ALL pattern, ie, CD10 (common ALL
antigen)-negative, strongly HLA-DR-positive, and CD19 (B4)- positive. The
presence of terminal deoxynucleotidyl transferase (TdT) at presentation was
positive in six patients' cells and negative in two. Two patients also
expressed the myeloid-associated markers CD33 (MY9) and CD15 (TG1), and
coexpression of CD19 and CD33 was confirmed in these two by using dual
marker flow cytometry (fluorescence- activated cell sorting). Electron
microscopic examination of the same two patients' cells showed the presence
of monocytoid blasts that labeled with the pan-B cell antibody B4 (CD19).
Short-term culture of one of these patients cells in the presence of
phorbol ester resulted in the majority of the cells exhibiting myeloid
markers, strong nonspecific esterase positivity, and phagocytic properties.
Cytogenetic analysis showed the common feature in 7 of 8 cases to be a
break in band 11q23. Molecular analysis of DNA from the blast cells of all
eight patients showed rearrangement of the immunoglobulin heavy-chain genes
in all cases without, however, any evidence of kappa light-chain
rearrangement. T cell receptor genes were present in the germline
configuration in all cases. Rearrangements of the c-ets 1 oncogene, which
maps to band 11q23, were not detected, thus providing no evidence for
involvement of this oncogene in the common disease process. Our data
indicate that although infant null ALL may present as a heterogeneous
disease the similarity of many features between cases suggests a common
derivation from a precursor cell sharing phenotypic and genotypic features
of both B and myeloid progenitor cells.
This article has been cited by other articles:
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| Copyright © 1988 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||