KU 812: a pluripotent human cell line with spontaneous erythroid terminal
maturation
M Nakazawa, MT Mitjavila, N Debili, N Casadevall, P Mayeux, P Rouyer-Fessard, A Dubart, PH Romeo, Y Beuzard and K Kishi
INSERM U 91, Hopital Henri Mondor, Creteil, France.
A human leukemic cell line KU 812 was recently established and described as
a basophilic cell line. In the present study we show that KU 812 and two of
its clones are at least bipotent: in addition to a minor component of
basophils, the majority of KU 812 cells belongs to the erythroid cell
lineage with a significant percentage (about 15%) of mature hemoglobinized
erythroblasts. This terminal differentiation is associated with the
synchronized synthesis of the main erythroid proteins, including
glycophorins, spectrin beta chain, band 3, and hemoglobin. The predominant
hemoglobins are adult, fetal, and Bart's hemoglobin. Adult hemoglobin
represented up to 75% of all hemoglobins in the KU 812 F clone in passages
containing a high number of mature erythroblasts. Transcripts of all human
globin chains were present with ten times less embryonic chain messenger
RNA (mRNA) than alpha-, beta- or gamma-chain mRNA. Hemin slightly increased
the total hemoglobin production of the cell line, especially gamma-globin
chain synthesis, but did not modify the percentage of hemoglobinized cells.
Phorbol myristate acetate (PMA) had a complex effect, inducing a proportion
of KU 812 cells to adhere to the plastic culture flask. The adherent cell
fraction expressed a very low level of specific erythroid proteins, but
their ultrastructure was consistent with immature erythroid cells. In
contrast, approximately 40% of the nonadherent cells were mature erythroid
cells. Cell-sorting experiments showed that this paradoxic effect of PMA is
mostly due to cell selection, the more mature cells being unable to adhere.
In addition, KU 812 F was found to be sensitive to erythropoietin, which
slightly increased its plating efficiency range (from 0% to 50%) in
semisolid medium and enhanced hemoglobin accumulation twofold. In binding
experiments using 125I erythropoietin, a single class of high-affinity Epo
receptors (Kd: 250 pM) was detected by binding with a density of 205
receptors per cell. The KU 812 cell line is therefore a unique model for
studying cell commitment toward different hematopoietic lineages and
erythroid differentiation.
Volume 73,
Issue 7,
pp. 2003-2013,
05/15/1989
Copyright © 1989 by The American Society of Hematology
