| Abstract |
A myeloid cell line, RED-3, has been established from the circulating
blasts of a patient with TdT(+) acute leukemia in second relapse. The
patient originally presented with T-ALL with 24% lymphoblasts by
morphology (FAB class L2). The blasts were polar block acid
phosphatase (ACP)(+), PAS(-), peroxidase (PX)(-), and non-specific esterase
(-) with 90% E-rosette formation. Blasts wore separated from blood by
Hypaque-Ficoll gradients and cultured at 10 cells/ml in RPMI 1640
supplemented with insulin, transferrin, selenium (ITS), and 20% fetal calf
serum (FBS). FBS was gradually withdrawn and by 8 wks the cells were
established in RPMI and ITS alone with a mean doubling time of 26 hrs.
Cells have been maintained for 15 mos at 37 Celsius, 7% CO2. Characterization
by histochemical stains and FACS-analysis showed that the cells in culture
were 9O%(+) for TdT and 95%(+) for the T-cell antigen Leu-3. However, the
cells were also positive for Sudan black, ACP, PAS, PX and for the myeloid
antigens M-1(97%), and My-7(99%). Retinoic acid (1 muM) and
dimethylformamide (60 mM) induced the cells to undergo myeloid maturation
and to acquire NBT reduction, additional myeloid antigens, Mo-1 (58%) and
OKM-1 (78%), and enhanced nonspecific binding of IgG1 and IgG2a but not IgM
indicating the presence of Fc receptors. The characteristics of this cell
line support previous reports that T-ALL blasts may retain the capacity
for myeloid differentiation.
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