Previous studies have suggested that Steel factor (SF) can influence the behavior of many
types of hematopoietic progenitor cells both in vivo and in vitro, although whether these may
include the most primitive populations of totipotent repopulating cells remains controversial.
To approach this question, we measured the number of Sca1" LinVVGA" cells, the number of
cells with demonstrable myeloid (long-term culture-initiating cell [LTC-1C]) or both myeloid
and lymphoid (LTC-IC) potential in 4-to 5-week-old long-term cultures containing irradiated …