title: CD23 defines two distinct subsets of immature B cells which differ in their responses to T cell help signals.
abstract: Transitional immature B cells undergo apoptosis and fail to proliferate in response to BCR cross-linking, thus representing a target for negative selection of potentially autoreactive B cells in vivo. In agreement with recent reports, transitional B cells were divided into developmentally contiguous subsets based on their surface expression of CD23. When transferred, CD23(+) transitional B cells readily localized to the splenic follicles and the outer PALS. Compared with CD23(-) transitional B cells, CD23(+) transitional B cells proliferated more vigorously and were rescued from BCR-induced apoptosis to a greater degree, by T cell help signals. However, both CD23(-) and CD23(+) transitional B cells failed to up-regulate CD86 (B7-2) in response to BCR ligation. These findings demonstrate that phenotypically defined subsets within the transitional B cell population are functionally distinct. Specifically, responsiveness to T cell help is a late acquisition corresponding to the stage when the B cells gain access to peripheral compartments enriched in antigen and activated T cells. The failure of transitional B cells to up-regulate CD86 to BCR-mediated stimulation suggests a unique interaction between transitional B cells and T cells with implications for tolerance in the T cell compartment.
authors.affiliation: Division of Rheumatology, Department of Medicine, 311 BRB II/III, 421 Curie Boulevard, University of Pennsylvania, PA 19104, USA.
authors.forename: James B
authors.initials: JB
authors.lastname: Chung
authors.forename: Richard A
authors.initials: RA
authors.lastname: Sater
authors.forename: Michele L
authors.initials: ML
authors.lastname: Fields
authors.forename: Jan
authors.initials: J
authors.lastname: Erikson
authors.forename: John G
authors.initials: JG
authors.lastname: Monroe
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis; D017209:Apoptosis; D016175:B-Lymphocyte Subsets / Q000502:physiology*; D051940:B7-2 Antigen; D002450:Cell Communication; D005260:Female; D008562:Membrane Glycoproteins / Q000096:biosynthesis; D051379:Mice; D008807:Mice, Inbred BALB C; D011947:Receptors, Antigen, B-Cell / Q000502:physiology; D017455:Receptors, IgE / Q000502:physiology*; D013601:T-Lymphocytes / Q000502:physiology*
chemical_list: D015703:Antigens, CD; D051940:B7-2 Antigen; C497965:Cd86 protein, mouse; D008562:Membrane Glycoproteins; D011947:Receptors, Antigen, B-Cell; D017455:Receptors, IgE