title: Impaired B-cell development at the pre-BII-cell stage in galectin-1-deficient mice due to inefficient pre-BII/stromal cell interactions.
abstract: Activation of the pre-B-cell receptor (pre-BCR) in the bone marrow depends on both tonic and ligand-induced signaling and leads to pre-BII-cell proliferation and differentiation. Using normal mouse bone marrow pre-BII cells, we demonstrate that the ligand-induced pre-BCR activation depends on pre-BCR/galectin-1/integrin interactions leading to pre-BCR clustering at the pre-BII/stromal cell synapse. In contrast, heparan sulfates, shown to be pre-BCR ligands in mice, are not implicated in pre-BCR relocalization. Inhibition of pre-BCR/galectin-1/integrin interactions has functional consequences, since pre-BII-cell proliferation and differentiation are impaired in an in vitro B-cell differentiation assay, without affecting cellular apoptosis. Most strikingly, although galectin-1-deficient mice do not show an apparent B-cell phenotype, the kinetics of de novo B-cell reconstitution after hydroxyurea treatment indicates a specific delay in pre-BII-cell recovery due to a decrease in pre-BII-cell differentiation and proliferation. Thus, although it remains possible that the pre-BCR interacts with other ligands, these results highlight the role played by the stromal cell-derived galectin-1 for the efficient development of normal pre-BII cells and suggest the existence of pre-BII-specific stromal cell niches in normal bone marrow.
authors.affiliation: Centre d'Immunologie de Marseille-Luminy, Université de Méditerranée, Marseille, France.
authors.forename: Marion
authors.initials: M
authors.lastname: Espeli
authors.forename: Stéphane J C
authors.initials: SJ
authors.lastname: Mancini
authors.forename: Caroline
authors.initials: C
authors.lastname: Breton
authors.forename: Françoise
authors.initials: F
authors.lastname: Poirier
authors.forename: Claudine
authors.initials: C
authors.lastname: Schiff