title: Repertoire-based selection into the marginal zone compartment during B cell development.
abstract: Marginal zone (MZ) B cells resemble fetally derived B1 B cells in their innate-like rapid responses to bacterial pathogens, but the basis for this is unknown. We report that the MZ is enriched in "fetal-type" B cell receptors lacking N regions (N(-)). Mixed bone marrow (BM) chimeras, made with adult terminal deoxynucleotidyl transferase (TdT)(+/+) and TdT(-/-) donor cells, demonstrate preferential repertoire-based selection of N(-) B cells into the MZ. Reconstitution of irradiated mice with adult TdT(+/+) BM reveals that the MZ can replenish N(-) B cells in adult life via repertoire-based selection and suggest the possibility of a TdT-deficient precursor population in the adult BM. The mixed chimera data also suggest repertoire-based bifurcations into distinct BM and splenic maturation pathways, with mature "recirculating" BM B cells showing a very strong preference for N(+) complementarity-determining region (CDR) 3 compared with follicular B cells. Because the T1 and MZ compartments are both the most enriched for N(-) H-CDR3, we propose a novel direct T1-->MZ pathway and identify a potential T1-MZ precursor intermediate. We demonstrate progressive but discontinuous repertoire-based selection throughout B cell development supporting multiple branchpoints and pathways in B cell development. Multiple differentiation routes leading to MZ development may contribute to the reported functional heterogeneity of the MZ compartment.
authors: Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037, USA.
authors: John B
authors: JB
authors: Carey
authors: Chantelle S
authors: CS
authors: Moffatt-Blue
authors: Lisa C
authors: LC
authors: Watson
authors: Amanda L
authors: AL
authors: Gavin
authors: Ann J
authors: AJ
authors: Feeney
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000378:metabolism*; D001854:Bone Marrow Cells / Q000166:cytology; D002454:Cell Differentiation; D002469:Cell Separation; D002678:Chimera; D005434:Flow Cytometry; D007136:Immunoglobulins / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008954:Models, Biological; D010641:Phenotype; D013154:Spleen / Q000378:metabolism
chemical_list: D007136:Immunoglobulins