CSF‐1 control of C‐FMS expression in normal human bone marrow progenitors

Abstract

We have previously shown (Zhou et al: Blood, 72:1870, 1988) that IL3, added with low concentrations of CSF-1 (1 ng/ml) to normal human CD34+ enriched cells, promoted the development of various types of colonies including those containing immature monocytes. However, when high concentrations of CSF-1 (20 ng/ml) were added alone or together with IL3, smaller colonies with mature macrophages were found. Here we show by in situ hybridization that IL3 allows the development, from CD34+ cells, of a subpopulation of immature progenitors which express the CSF-1 receptor (c-fms) mRNA. The expression of c-FMS protein was also substantiated by immunocytochemical studies using anti-c-fms antibody. The percentage of c-fms positive cells peaked at day 7 and began to decrease thereafter. When anti-CSF-1 antibodies were included in the culture, the decrease in c-fms mRNA after day 7 was abrogated. This indicated that endogenous CSF-1 was produced as CD34+ cells developed into monocytes or progenitors of monocytes and that CSF-1 modulates c-fms expression. We further demonstrated that when a high dose of CSF-1 (20 ng/ml) was added at day 7 to IL3-stimulated CD34+ cells, a rapid down-regulation of c-fms mRNA and protein was seen. No down-regulation was observed with low concentration of CSF-1 (1 ng/ml). The possibility that different concentrations of CSF-1 could modulate the development of monocytic progenitors is discussed.

Synergistic up-regulation of the myeloid-specific promoter for the macrophage colony-stimulating factor receptor by AML1 and the t(8;21) fusion protein may contribute to leukemogenesis.

“…Expression of the M-CSF receptor is very low in hematopoietic stem cells and increases as the cells begin to differentiate (37)(38)(39). Premature expression in early progenitors may cause aberrant proliferation.…”

“…Early myeloid cells make very little M-CSF receptor mRNA compared with mature cells (37)(38)(39) that have not yet been identified would be altered due to the expression of the t(8;21) fusion protein, AMLl-ETO. Further studies will be necessary to identify these target genes and also elucidate the mechanism by which AMLl-ETO exerts its effects.…”

Release from quiescence of CD34+ CD38- human umbilical cord blood cells reveals their potentiality to engraft adults.

“…We have demonstrated that the low concentrations of cytokines used in these studies were necessary to avoid down-regulation of some receptors on immature cells (6). These low concentrations of cytokines were always found equally optimal for bone marrow and umbilical cord blood early progenitors.…”

p21cip1 mRNA is controlled by endogenous transforming growth factor-?1 in quiescent human hematopoietic stem/progenitor cells

“…The complete procedure is based on the methods described by Angerer et al (1987) and Bernaudin et al (1988) and has been detailed extensively in previous reports (Panterne et al, 1993. The p21 cip1 probe is a 0.6-kb HindIII/XbaI insert in a RC/CMV plasmid (In Vitrogen), a generous gift of Dr. J. M. Blanchard, Montpellier, France.…”

“…Because most adult human hematopoietic CD34 ϩ progenitors are in the G 0 /G 1 phase (Gothot et al, 1997), we were interested in how p21 cip1 mRNA was regulated when quiescent cells became competent to go through the cell cycle and what the effect of TGF-␤1 on p21 cip1 mRNA modulation was. Because these primitive cells usually express low levels of mRNA or proteins controlling their growth, such as cytokine receptors Gothot et al, 1997), we have used a sensitive and semiquantitative in situ hybridization (ISH) method developed in our laboratory which permits the detection of a few mRNA copies in single isolated progenitors (Panterne et al, 1993. Our results demonstrate that the CDKI p21 cip1 is not only regulated in differentiating cells (Steinman et al, 1998;Taniguchi et al, 1999), but also in primitive undifferentiated pro-genitors to control exit from quiescence.…”