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M Carlsson, TH Totterman, P Matsson and K Nilsson
Department of Pathology, University Hospital, Uppsala, Sweden.
The cell cycle transition and differentiation-associated surface antigen
expression was studied in a clone of B cell chronic lymphocytic leukemia
(B-CLL) with phenotypic properties similar to those of resting B
lymphocytes. Differentiation was induced with TPA (12-O-tetradecanoyl-
phorbol-13-acetate) and defined and quantitated by morphological and
functional markers. Changes in the cell cycle position were determined by
flow cytometry of acridine orange-stained cells. The uninduced B-CLL cells
represented a homogeneous population with the same cell cycle position (GO)
as resting normal peripheral blood lymphocytes. After five days of TPA
stimulation, 56% of the B-CLL cells were found in G1A, 9% in G1B, and 3% in
the S + G2/M phase, of which 2% was accounted to proliferating T cells. The
cell cycle transition of the differentiating B-CLL cells was also examined
using cell cycle-associated surface antigens as markers. HLA-DR and CD23
antigens were present already on noninduced cells. The former had a high
constant expression, while the amount of CD23 increased upon induction. The
4F2 antigen was absent on noninduced cells but present on 86% of the
induced cells. HH1 (CD37) was expressed by the majority of the cells before
TPA treatment and decreased to almost undetectable levels within 24 hours.
Two antigens related to late stages of the cell cycle, the interleukin 2
(IL 2; CD25) and the transferrin receptor, were present on about 20% of the
induced cells. Experiments with enriched T cells showed that T but not B
cells incorporated 3H-thymidine. Taken together these results and previous
work on the induction of the protooncogene c-myc and c-fos suggest that
this B-CLL clone represents GO cells that undergo differentiation without
concomitant proliferation when exposed to TPA.
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| Copyright © 1988 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||