| Abstract |
Permanent cell lines are important tools for studying the biology of human
leukemia. Only 5 chronic myeloid leukemia (CML) cell lines carrying the
Philadelphia (Ph1) chromosome have been established. We report the
establishment of RWLeu-4, a Ph1-positive cell line derived from the
peripheral blood of a patient in the blastic phase of CML. The RWLeu-4
cell is an undifferentiated blast with a high nucleocytoplasmic ratio,
basophillic cytoplasm and two or more nucleoli. The doubling time is 33
hrs. The cloning efficiency is 39%. Peroxidase and esterase stains are
positive. On electron microscopy, irregularly shaped nuclei, distinct
nucleoli and prominent cytoplasmic granules are observed. Karyotypic
analysis demonstrates a modal chromosome number of 56. The Ph1 chromosome
(22 q-) is present. Other rearrangements include 7p+, 12p+ and 17p+. RWLeu-4
cells are negative for Epstein-Barr virus as determined by DNA dot
hybridization Neither IgG nor IgM is detected on the cell surface. Five
percent of the cells are Ia antigen positive and 100% are beta-2
microglobulin positive. Both dimethyl sulfoxide and N-methylformamide
induce myeloid maturation as determined by morphological changes and NBT
dye reduction. In the presence of TPA, the cells become adherent, are
strongly nonspecific esterase positive, and differentiate into macrophage-
appearing cells. RWLeu-4, a Ph1-positive CML cell line with myeloid
characteristics, should prove useful in studying the biology and
differentiation of CML.
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