OBJECTIVETo explore the expression, characteristics and roles of macrophage colony-stimulating factor receptor (M-CSF-R) in human leukemia cell lines.

METHODSPeripheral blood mononuclear cells (PBMCs) collected from 3 healthy persons, cord blood mononuclear cells (CBMCs) collected from 5 healthy persons and 4 human myelomonocytic leukemia cell lines including J6-1, J6-2, K562 and HL-60 were studied by using ABC immunoperoxidaes assay, indirect immunofluorescene staining, flow cytometry, and Western blot.

RESULTSM-CSF-R was noticed to be localized in the cytoplasm, nucleus and at the membrane in 4 human leukemia cell lines; expression of M-CSF-R was not detected in normal human PBMCs without PHA stimulation. Human PBMCs stimulated by PHA expressed a low level of M-CSF-R. Frequencies of membrane bound M-CSF-R (M-CSF-mR) expression in J6-1, J6-2, K562 and HL-60 were 78.9%, 72.6%, 54.9% and 58.0% respectively. Frequencies of cytoplasm and nucleus associated M-CSF-R (M-CSF-cnR) were 52.3%, 44.3%, 28.0% and 65.3% respectively. One form of M-CSF-R with a molecular weight of 120 000 was detected both in the cytoplasm and nucleus of HL-60 cells. The half-life of M-CSF-cnR in leukemia cells mentioned above was longer than that of corresponding M-CSF-R in stimulated CBMCs, and the half-life of M-CSF-mR in leukemia cells was extended except that of M-CSF-mR in K562 cells. Both anti-M-CSF-R monoclonal antibody and recombinant human M-CSF soluble receptor could cause the growth arrest of HL-60 cell in G(0)/G(1) phase, and could inhibit the formation of colony of HL-60 cell in soft agarose.

CONCLUSIONSExpression of M-CSF-R in leukemia cells is heterogeneous. The accumulation of cellular M-CSF-R results in the low degradation rate of cellular M-CSF-R in leukemia cells, which could be a potential mitotic signal. Signal mediated by M-CSF-R is important and necessary for the growth of HL-60 cell.