Perisinusoidal B cells in the bone marrow participate in T-independent responses to blood-borne microbes.
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.
Cariappa
Annaiah
A
Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02129, USA.
Mazo
Irina B
IB
Chase
Catharine
C
Shi
Hai Ning
HN
Liu
Haoyuan
H
Li
Qian
Q
Rose
Harris
H
Leung
Harry
H
Cherayil
Bobby J
BJ
Russell
Paul
P
von Andrian
Ulrich
U
Pillai
Shiv
S
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*
D018398:Homeodomain Proteins; D007072:Immunoglobulin D; D007075:Immunoglobulin M; D017464:Receptors, Complement 3d; C064658:RAG-1 protein; D003564:Cytidine Deaminase