title: Adherence of normal and neoplastic human B cell precursors to the bone marrow microenvironment.
abstract: The early development of B lineage cells occurs in the bone marrow in close association with fibroblast-like accessory cells. The integrin VLA-4 is preferentially expressed by B cell precursors and mediates adhesion of B cell precursors to bone marrow derived fibroblasts (BM-FB), which express a VLA-4 counter/receptor, VCAM-1. The functional importance of this adhesion interaction is suggested by the inhibition by anti-VLA-4 antibody of in vitro proliferation of B cell progenitor colonies grown with a BM-FB adherent layer. In order to compare adhesion requirements of normal versus neoplastic human B cell precursors, quantitative expression of adhesion proteins by primary human B cell precursor acute lymphoblastic leukemia (BCP-ALL) cells was studied by flow cytometry. BCP-ALL cells expressed VLA-4 and VLA-5 at similar levels as normal immature B cell precursors. However, other adhesion molecules, particularly CD44, were overexpressed by the leukemic cells relative to their normal counterparts. Similar to normal B cell precursors, adhesion of BCP-ALL cells to BM-FB was inhibited by antibodies to VLA-4 and VCAM-1. These results suggest that the ordered program of adhesion protein expression and functional activation during B cell development is at least partially intact in BCP-ALL cells, and may play a role in tissue localization and growth of the neoplastic cells. The focal pattern of spreading of adherent BCP-ALL cell lines on individual cells in the BM-FB adherent layer suggests functional heterogeneity in the bone marrow microenvironment that may be essential in regulating normal and neoplastic lymphopoiesis.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, New York 14642.
authors.forename: D H
authors.initials: DH
authors.lastname: Ryan
mesh_terms: D015703:Antigens, CD / Q000032:analysis / Q000096:biosynthesis*; D001402:B-Lymphocytes / Q000276:immunology* / Q000473:pathology; D001853:Bone Marrow / Q000276:immunology* / Q000473:pathology; D002051:Burkitt Lymphoma / Q000276:immunology* / Q000473:pathology; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000032:analysis / Q000096:biosynthesis*; D002478:Cells, Cultured; D005347:Fibroblasts / Q000276:immunology / Q000473:pathology; D006412:Hematopoietic Stem Cells / Q000276:immunology* / Q000473:pathology; D006801:Humans; D018799:Intercellular Adhesion Molecule-1; D008954:Models, Biological; D017469:Receptors, Fibronectin / Q000032:analysis / Q000096:biosynthesis; D016029:Receptors, Very Late Antigen / Q000032:analysis / Q000096:biosynthesis; D012867:Skin / Q000276:immunology / Q000473:pathology
chemical_list: D015703:Antigens, CD; D015815:Cell Adhesion Molecules; D017469:Receptors, Fibronectin; D016029:Receptors, Very Late Antigen; D018799:Intercellular Adhesion Molecule-1