Interleukin-3 and Flt3-ligand induce adhesion of Baf3/Flt3 precursor B-lymphoid cells to fibronectin via activation of VLA-4 and VLA-5.
Adhesion of hematopoietic cells to extracellular matrix components is important for blood cell development. However, little is known regarding the potential influence of IL-3 on this process for precursor B cells and Flt3-ligand has not yet been implicated in induction of adhesion of any blood cell types to extracellular matrix components. Therefore, we examined the characteristics of cytokine-induced cell adhesion to fibronectin (FN), using as a model the murine precursor B cell line, Baf3, a factor-dependent cell line requiring IL-3 for both growth and survival. Since factor-dependent hematopoietic cell lines expressing Flt3 receptor are extremely rare, we also studied Baf3/Flt3, a subline of Baf3 transduced with the Flt3 receptor gene. IL-3 induced adhesion of Baf3 and Baf3/Flt3 cells to FN, while Flt3-ligand induced adhesion of Baf3/Flt3 cells only. Whereas both Baf3 and Baf3/Flt3 cells expressed VLA-4 and -5 integrins as FN receptors, expression levels of VLA-4 and -5 were not affected by IL-3 or Flt3-ligand treatment. However, blocking experiments using anti-integrin antibodies showed that cytokine-induced adhesion of cells depended on both VLA-4 and -5 suggesting that IL-3 and Flt3-ligand activated these integrins. PI-3 kinase inhibitor wortmannin, PKC inhibitor H-7, or PKA inhibitor HA1004 did not suppress adhesion induced by IL-3 or Flt3-ligand; in contrast, PLC inhibitor U-73122 did suppress adhesion, suggesting the possibility that PLC, but not PI-3 kinase, PKC, or PKA, may be involved in this process. Since it is known that IL-3 and Flt3-ligand receptors are expressed on precursor B cells, and these receptors are downregulated during B cell maturation of primary cells, the induction of precursor B cell adhesion to FN by IL-3 and Flt3-ligand may contribute a mechanism by which precursor B cells adhere to bone marrow stroma, thereby influencing their development.
Department of Microbiology/Immunology, Indiana University School of Medicine, Indianapolis 46202, USA.
H
H
Shibayama
N
N
Anzai
A
A
Ritchie
S
S
Zhang
C
C
Mantel
H E
HE
Broxmeyer
D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology* / Q000187:drug effects / Q000276:immunology*; D002448:Cell Adhesion / Q000187:drug effects* / Q000276:immunology; D002454:Cell Differentiation / Q000187:drug effects / Q000276:immunology; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D005353:Fibronectins / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000276:immunology*; D039041:Integrin alpha4beta1; D016023:Integrins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007377:Interleukin-3 / Q000494:pharmacology*; D008565:Membrane Proteins / Q000494:pharmacology*; D051379:Mice; D011760:Pyrrolidinones / Q000494:pharmacology; D017469:Receptors, Fibronectin / Q000378:metabolism*; D016201:Receptors, Lymphocyte Homing / Q000378:metabolism*; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
D004791:Enzyme Inhibitors; D004963:Estrenes; D005353:Fibronectins; D039041:Integrin alpha4beta1; D016023:Integrins; D007377:Interleukin-3; D008565:Membrane Proteins; D011760:Pyrrolidinones; D017469:Receptors, Fibronectin; D016201:Receptors, Lymphocyte Homing; C084881:flt3 ligand protein; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D010738:Type C Phospholipases