IL-7 stimulates CSF-induced proliferation of murine bone marrow macrophages and Mac-1+ myeloid progenitors in vitro.
The role of IL-7 as an important stimulator of the growth of B and T cell precursors, as well as mature T cells, is well established. In contrast, the role of IL-7 in myelopoiesis has not been characterized thoroughly, and thus, IL-7 has been regarded as a lymphoid lineage-restricted cytokine. However, we have recently reported that IL-7 enhanced CSF-induced myeloid proliferation of primitive murine hematopoietic (Lin-Sca-1+) progenitors, whereas IL-7 did not affect significantly the proliferation of a population of more mature (Lin-) progenitors. The present study was initiated to investigate further whether IL-7 might affect CSF-induced proliferation of subpopulations of committed myeloid progenitors as well as mature bone marrow macrophages. IL-7 enhanced macrophage colony-stimulating factor (CSF-1)-induced colony formation of single bone marrow macrophages 90%, whereas IL-7 alone had no effect. Furthermore, IL-7, in a concentration-dependent manner, increased the proliferation of mononuclear cells expressing the Mac-1 Ag (Mac-1+ mononuclear cells (MNC); CD11b) up to fivefold in response to CSF-1, granulocyte macrophage-CSF (GM-CSF), or IL-3. In contrast, no effect of IL-7 was observed on Mac-1- MNC. The synergistic effect of IL-7 on Mac-1+ MNC was caused by an increase in macrophage colonies (CFU-M) and mixed granulocyte-macrophage colonies (CFU-GM), whereas the total number of granulocyte colonies (CFU-G) was not affected. This suggests that IL-7 can provide proliferative signals to Mac-1+ progenitors with a macrophage potential, but not to progenitors committed to pure granulocyte differentiation.
Jacobsen
F W
FW
Department of Immunology, Norwegian Radium Hospital, Oslo.
Veiby
O P
OP
Jacobsen
S E
SE
D000818:Animals; D001854:Bone Marrow Cells; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006410:Hematopoiesis / Q000187:drug effects*; D015851:Interleukin-7 / Q000494:pharmacology*; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D016177:Macrophage-1 Antigen / Q000032:analysis; D008264:Macrophages / Q000166:cytology*; D051379:Mice; D008810:Mice, Inbred C57BL; D017452:Receptors, IgG / Q000378:metabolism
D015851:Interleukin-7; D016177:Macrophage-1 Antigen; D017452:Receptors, IgG; D016173:Macrophage Colony-Stimulating Factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor