Fibrinogen cooperates with cytokines to induce interleukin-6 receptor mRNA expression in human hematopoietic CD34+ progenitors.
We have previously demonstrated that purified human fibrinogen (Fg), a major plasma component removed during serum preparation, shows mitogenic properties towards lymphoma cells and normal human hematopoietic progenitors. Indeed, adding Fg with IL-3 to a serum-containing medium stimulates growth of human CD34+ progenitors. In this report, we show in serum-free medium, that this stimulating effect only occurs in the presence of IL-6. To clarify the cooperative effect between Fg and IL-6, the kinetics of IL-6 receptor (IL-6R) mRNA expression in CD34+ cells have been analyzed by semi-quantitative in situ hybridization. In the presence of both IL-3 and Fg, more cells express IL-6R mRNA, and this expression per cell is significantly greater than with each factor added separately. These results suggest that Fg does not promote the growth of normal cells by itself, but sensitizes the cells to cytokines. Fg behaves not as a "progression" factor but as a typical "competence" factor, which induces a faster and greater IL-6R expression in early human hematopoietic progenitors by cooperating with other cytokines.
Laboratoire de Biologie des Cellules Souches Somatiques Humaines, UPR 1983 du CNRS, IFC1, 7, rue Guy-Moquet, BP 8, 94801 Villejuif Cedex, France.
A
A
Hatzfeld
B
B
Panterne
N O
NO
Fortunel
M N
MN
Monier
J A
JA
Hatzfeld
D018952:Antigens, CD34 / Q000276:immunology*; D005340:Fibrinogen / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D017403:In Situ Hybridization; D015850:Interleukin-6 / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics*; D019947:Receptors, Interleukin-6 / Q000235:genetics*
D018952:Antigens, CD34; D015850:Interleukin-6; D012333:RNA, Messenger; D019947:Receptors, Interleukin-6; D005340:Fibrinogen