title: Transitional B cells: step by step towards immune competence.
abstract: Transitional B cells mark the crucial link between bone-marrow (BM) immature and peripheral mature B cells. Examination reveals unexpected heterogeneity, consisting of contiguous subsets with phenotypic and functional differences. Data point to the late transitional B-cell stage as a crucial juncture at which developing B cells gain access to splenic follicles, become responsive to T-cell help and lose sensitivity to negative selection, characterizing the immature B-cell response to B-cell antigen receptor (BCR) signaling in vitro and in vivo. The biological and molecular processes directing maturation through this stage are becoming clearer through biochemical studies and murine models deficient in various components of the BCR signaling pathway.
authors.affiliation: Division of Rheumatology, Department of Medicine, University of Pennsylvania, Philadelphia 19104, USA.
authors.forename: James B
authors.initials: JB
authors.lastname: Chung
authors.forename: Michael
authors.initials: M
authors.lastname: Silverman
authors.forename: John G
authors.initials: JG
authors.lastname: Monroe
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology*; D002454:Cell Differentiation / Q000276:immunology*; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology; D006801:Humans; D007121:Immunocompetence; D010641:Phenotype; D011947:Receptors, Antigen, B-Cell; D013154:Spleen / Q000276:immunology
chemical_list: D011947:Receptors, Antigen, B-Cell