title: Characterization of a late transitional B cell population highly sensitive to BAFF-mediated homeostatic proliferation.
abstract: We have characterized a distinct, late transitional B cell subset, CD21(int) transitional 2 (T2) B cells. In contrast to early transitional B cells, CD21(int) T2 B cells exhibit augmented responses to a range of potential microenvironmental stimuli. Adoptive transfer studies demonstrate that this subset is an immediate precursor of both follicular mature and marginal zone (MZ) B cells. In vivo, a large percentage of CD21(int) T2 B cells has entered the cell cycle, and the cycling subpopulation exhibits further augmentation in mitogenic responses and B cell-activating factor of the TNF family (BAFF) receptor expression. Consistent with these features, CD21(int) T2 cells exhibit preferential responses to BAFF-facilitated homeostatic signals in vivo. In addition, we demonstrate that M167 B cell receptor (BCR) idiotypic-specific B cells are first selected within the cycling CD21(int) T2 population, ultimately leading to preferential enrichment of these cells within the MZ B cell compartment. These data, in association with the coordinate role for BAFF and microenvironmental cues in determining the mature BCR repertoire, imply that this subset functions as a unique selection point in peripheral B cell development.
authors.affiliation: Department of Pediatrics, University of Washington School of Medicine, Seattle, WA 98195, USA.
authors.forename: Almut
authors.initials: A
authors.lastname: Meyer-Bahlburg
authors.forename: Sarah F
authors.initials: SF
authors.lastname: Andrews
authors.forename: Karl O A
authors.initials: KO
authors.lastname: Yu
authors.forename: Steven A
authors.initials: SA
authors.lastname: Porcelli
authors.forename: David J
authors.initials: DJ
authors.lastname: Rawlings
mesh_terms: D000818:Animals; D018941:Antigens, CD19 / Q000096:biosynthesis; D053264:B-Cell Activating Factor / Q000502:physiology*; D001402:B-Lymphocytes / Q000378:metabolism*; D002453:Cell Cycle; D049109:Cell Proliferation; D049452:Green Fluorescent Proteins / Q000378:metabolism; D017493:Leukocyte Common Antigens / Q000096:biosynthesis; D051917:Leukosialin / Q000096:biosynthesis; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D010641:Phenotype; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism; D017464:Receptors, Complement 3d / Q000096:biosynthesis
chemical_list: D018941:Antigens, CD19; D053264:B-Cell Activating Factor; D051917:Leukosialin; D011947:Receptors, Antigen, B-Cell; D017464:Receptors, Complement 3d; C505719:TNFSF13B protein, human; D049452:Green Fluorescent Proteins; D017493:Leukocyte Common Antigens