Stem Cell Factor as a Single Agent Induces Selective Proliferation of the Philadelphia Chromosome Positive Fraction of Chronic Myeloid Leukemia CD341 Cells

The interaction between p145c-KIT and p210bcr-abl in trans-duced cell lines, and the selective outgrowth of normal progenitors during long-term culture of chronic myeloid leukemia (CML) cells on stroma deficient in stem-cell factor (SCF) suggests that the response of CML cells to SCF may be abnormal. We examined the proliferative effect of SCF(100 ng/mL), provided as the sole stimulus, on individual CD341 cells from five normal donors and five chronic-phase CML patients. Forty-eight percent of isolated single CML CD341 cells proliferated after 6 days of culture to a mean of 18 cells, whereas only 8 % of normal CD341 cells proliferated (mean number of cells generated was 4). SCF, as a single agent, supported the survival and expansion of colony-forming unit–granulocyte-macrophage (CFU-GM) from CML CD341CD381 cells and the more primitive CML CD341CD38