Hematopoietic precursors resistant to treatment with 4-
hydroperoxycyclophosphamide: requirement for an interaction with marrow
stroma in addition to hematopoietic growth factors for maximal generation
of colony-forming activity
SD Rowley, C Brashem-Stein, R Andrews and ID Bernstein
Division of Clinical Research, Fred Hutchinson Cancer Research Center,
Seattle, WA 98104.
We tested the ability of CD34+lin- precursor cells isolated from marrow
after treatment with 4-hydroperoxycyclophosphamide (4HC) to generate
colony-forming cells (CFC). In liquid cultures, recombinant human stem cell
factor (SCF), in combination with interleukin-1 (IL-1), IL-3, IL- 6,
granulocyte-macrophage colony-stimulating factor, or granulocyte
colony-stimulating factor caused untreated, but not 4HC-treated, CD34+lin-
cells to form CFC. However, generation of CFC from CD34+lin- cells treated
with 60 micrograms/mL of 4HC was possible in the presence of an irradiated
allogeneic stromal cell layer. This generation was increased when
combinations of hematopoietic growth factors including SCF and IL-3 were
added. Maximal generation of CFC was seen after 11 to 21 days of culture.
At that time, generation of CFC from CD34+lin- 4HC- treated cells equalled
that from untreated cells. The phenotype of these 4HC-resistant CD34+lin-
precursors was also further defined as CD38-. These studies show that the
generation of CFC from the 4HC- resistant, highly immature population of
CD34+lin- cells requires an as yet undefined interaction with marrow stroma
in addition to known hematopoietic growth factors.
Volume 82,
Issue 1,
pp. 60-65,
07/01/1993
Copyright © 1993 by The American Society of Hematology
