title: Perisinusoidal B cells in the bone marrow participate in T-independent responses to blood-borne microbes.
abstract: Mature recirculating B cells are generally assumed to exist in follicular niches in secondary lymphoid organs, and these cells mediate T-dependent humoral immune responses. We show here that a large proportion of mature B lymphocytes occupy an anatomically and functionally distinct perisinusoidal niche in the bone marrow. Perisinusoidal B cells circulate freely, as revealed by parabiosis studies. However, unlike their counterparts in the follicular niche, these cells are capable of being activated in situ by blood-borne microbes in a T-independent manner to generate specific IgM antibodies. The bone marrow represents a unique type of secondary lymphoid organ in which mature B cells are strategically positioned in the path of circulating microbes.
authors.affiliation: Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02129, USA.
authors.forename: Annaiah
authors.initials: A
authors.lastname: Cariappa
authors.forename: Irina B
authors.initials: IB
authors.lastname: Mazo
authors.forename: Catharine
authors.initials: C
authors.lastname: Chase
authors.forename: Hai Ning
authors.initials: HN
authors.lastname: Shi
authors.forename: Haoyuan
authors.initials: H
authors.lastname: Liu
authors.forename: Qian
authors.initials: Q
authors.lastname: Li
authors.forename: Harris
authors.initials: H
authors.lastname: Rose
authors.forename: Harry
authors.initials: H
authors.lastname: Leung
authors.forename: Bobby J
authors.initials: BJ
authors.lastname: Cherayil
authors.forename: Paul
authors.initials: P
authors.lastname: Russell
authors.forename: Ulrich
authors.initials: U
authors.lastname: von Andrian
authors.forename: Shiv
authors.initials: S
authors.lastname: Pillai
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D016470:Bacteremia / Q000276:immunology*; D001854:Bone Marrow Cells / Q000166:cytology / Q000276:immunology*; D002465:Cell Movement; D003564:Cytidine Deaminase / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics; D007072:Immunoglobulin D / Q000276:immunology; D007075:Immunoglobulin M / Q000276:immunology; D008213:Lymphocyte Activation; D051379:Mice; D018345:Mice, Knockout; D017464:Receptors, Complement 3d / Q000378:metabolism; D013154:Spleen / Q000201:enzymology; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D018398:Homeodomain Proteins; D007072:Immunoglobulin D; D007075:Immunoglobulin M; D017464:Receptors, Complement 3d; C064658:RAG-1 protein; D003564:Cytidine Deaminase