Clonal growth of murine pre-B colony-forming cells and their targeted
infection by a retroviral vector: dependence on interleukin-7
DE Williams, AE Namen, DY Mochizuki and RW Overell
Department of Experimental Hematology, Immunex Corporation, Seattle, WA
98101.
The cDNA for interleukin-7 (IL-7) was recently isolated from a stromal cell
line derived from a long-term B-lymphoid culture. We report that purified
recombinant murine IL-7 can promote the clonal growth in semi- solid
culture of a subpopulation of cells expressing the B220 surface antigen
from normal murine bone marrow. These colony-forming cells (CFC- Pre-B)
give rise to colonies of 20 to 1,000 cells after 7 days in culture.
Morphologic examination of cells within the colonies showed a
characteristic lymphoid morphology, and histochemical examination
demonstrated an absence of markers associated with granulocyte, macrophage,
eosinophil, or megakaryocyte differentiation, as well as an absence of
hemoglobinization (indicative or erythroid differentiation). IL-7 was found
to specifically enhance the infection of CFC-Pre-B but not CFU-GM when the
cytokine was present during a 48-hour co- cultivation period between
irradiated, retrovirus-producing psi 2 clones and normal mouse bone marrow
cells. In contrast, IL-3 enhanced the infection of CFU-GM but not
CFC-Pre-B. Thymidine suiciding studies suggest that this targeted infection
is due to specific induction of cycling of CFC-Pre-B by IL-7 and CFU-GM by
IL-3. These data demonstrate that IL-7 can target retroviral infection into
a specific subpopulation of early B-lymphoid cells (CFC-Pre-B), and that
IL-7 cannot directly promote the in vitro clonal growth of myeloid
committed progenitor cells (ie, CFU-GM).
Volume 75,
Issue 5,
pp. 1132-1138,
03/01/1990
Copyright © 1990 by The American Society of Hematology
