title: Regulation of human B-cell precursor adhesion to bone marrow stromal cells by cytokines that exert opposing effects on the expression of vascular cell adhesion molecule-1 (VCAM-1).
abstract: Self-renewal and differentiation of B-cell precursors is dependent on interactions with bone marrow (BM) stromal cells and associated extracellular matrix. We have recently developed an interleukin (IL)-7-dependent, BM-derived stromal cell culture that supports the growth of normal human B-cell precursors. In the current study, we have characterized the constitutive expression, cytokine-regulated expression, and function of adhesion molecules on BM stromal cells that are critical for adhesion of B-cell precursors. Flow cytometric analysis showed that cultured adult BM stromal cells expressed higher constitutive levels of vascular cell adhesion molecule (VCAM)-1 than intercellular adhesion molecule (ICAM)-1 (CD54). IL-1 beta upregulated VCAM-1 and CD54 in a dose-dependent manner, whereas IL-4 upregulated VCAM-1, but had no effect on CD54. In contrast, transforming growth factor (TGF)-beta decreased the level of BM stromal cell VCAM-1. Using an assay to measure the adhesion of 51Cr-labeled B-cell precursors to BM stromal cells, we observed a direct correlation between cytokine-regulated levels of VCAM-1 and the capacity of stromal cells to support the adhesion of B-cell precursors. Blocking studies using a panel of monoclonal antibodies (MoAb) showed that adhesion of B-cell precursors to untreated and cytokine-treated (IL-1 beta, IL-4) BM stromal cells was mediated by very late antigen (VLA)-4 (CD49d/CD29) and VCAM-1. Adhesion of B-cell precursors could also be enhanced by direct stimulation with MoAb to the CD29 subunit. Our collective results indicate that B-cell precursor/BM stromal cell adhesion is mediated by a VLA-4-VCAM-1 interaction, which in turn can be regulated at the level of the BM stromal cell by cytokines that specifically increase or decrease cell surface VCAM-1.
authors.affiliation: Department of Laboratory Medicine & Pathology, University of Minnesota Medical School, Minneapolis 55455.
authors.forename: B N
authors.initials: BN
authors.lastname: Dittel
authors.forename: J B
authors.initials: JB
authors.lastname: McCarthy
authors.forename: E A
authors.initials: EA
authors.lastname: Wayner
authors.forename: T W
authors.initials: TW
authors.lastname: LeBien
mesh_terms: D000328:Adult; D015703:Antigens, CD / Q000032:analysis; D001402:B-Lymphocytes / Q000187:drug effects / Q000502:physiology*; D001853:Bone Marrow / Q000187:drug effects / Q000502:physiology*; D001854:Bone Marrow Cells; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology*; D015815:Cell Adhesion Molecules / Q000096:biosynthesis / Q000378:metabolism*; D016207:Cytokines / Q000494:pharmacology*; D005333:Fetus; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D007378:Interleukins / Q000494:pharmacology*; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D011994:Recombinant Proteins / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D019010:Vascular Cell Adhesion Molecule-1
chemical_list: D015703:Antigens, CD; D015815:Cell Adhesion Molecules; D016207:Cytokines; D007378:Interleukins; D008070:Lipopolysaccharides; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D019010:Vascular Cell Adhesion Molecule-1; D016222:Fibroblast Growth Factor 2; D007371:Interferon-gamma