title: [IgM+IgD+CD27+ B cells in human: an essential role in the protection against encapsulated bacteria].
abstract: In humans, CD27+ blood B cells with mutated immunoglobulin (Ig) receptors comprise two major populations: isotype-switched memory cells (IgG+ or IgA+CD27+) and IgM+IgD+CD27+ cells. While switched CD27+ cells are generated in germinal centers (GC) by T-dependent (TD) responses, the origin of IgM+IgD+CD27+ cells is still controversial. Data including ours support the view that these cells can develop and mutate along a GC-independent pathway and that they represent circulating marginal zone B (MZB) cells involved in T-independent (TI) responses. Our data provide evidence for a developmental diversification of these MZB cells, at least in very young children, outside of TD and TI immune responses. The identification of a human MZB cell precursor with NOTCH2-dependent differentiation properties further argue in favor of the existence of a MZB cell lineage in humans, like in rodents. At last, a role for Toll-like receptors in the development and/or maintenance of IgM+IgD+CD27+ B cells is proposed.
authors.affiliation: Institut Necker-Enfants malades (INEM), Inserm U1151, CNRS UMR 8253, université Paris Descartes, Sorbonne Paris Cité, faculté de médecine, site Broussais, 14, rue Maria Helena Viera Da Silva, 75993 Paris Cedex 14, France.
authors.forename: Sandra
authors.initials: S
authors.lastname: Weller
authors.affiliation: Institut Necker-Enfants malades (INEM), Inserm U1151, CNRS UMR 8253, université Paris Descartes, Sorbonne Paris Cité, faculté de médecine, site Broussais, 14, rue Maria Helena Viera Da Silva, 75993 Paris Cedex 14, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Descatoire
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism / Q000502:physiology*; D001419:Bacteria / Q000276:immunology* / Q000472:pathogenicity; D016667:Bacterial Capsules / Q000276:immunology*; D002454:Cell Differentiation / Q000276:immunology; D006801:Humans; D007111:Immunity, Cellular / Q000502:physiology*; D007072:Immunoglobulin D / Q000378:metabolism; D007075:Immunoglobulin M / Q000378:metabolism; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7 / Q000378:metabolism
chemical_list: D007072:Immunoglobulin D; D007075:Immunoglobulin M; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7