title: Somatically diversified and proliferating transitional B cells: implications for peripheral B cell homeostasis.
abstract: The peripheral B cell compartment in mice and humans is maintained by continuous production of transitional B cells in the bone marrow. In other species, however, including rabbits, B lymphopoiesis in the bone marrow abates early in life, and it is unclear how the peripheral B cell compartment is maintained. We identified transitional B cells in rabbits and classified them into T1 (CD24(high)CD21(low)) and T2 (CD24(high)CD21(+)) B cell subsets. By neutralizing B cell-activating factor in vivo, we found an arrest in peripheral B cell development at the T1 B cell stage. Surprisingly, T1 B cells were present in GALT, blood, and spleen of adult rabbits, long after B lymphopoiesis was arrested. T1 B cells were distinct from their counterparts in other species because they are proliferating and the Ig genes are somatically diversified. We designate these newly described cells as T1d B cells and propose a model in which they develop in GALT, self renew, continuously differentiate into mature B cells, and thereby maintain peripheral B cell homeostasis in adults in the absence of B lymphopoiesis.
authors.affiliation: Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL 60153, USA.
authors.forename: Venkata A
authors.initials: VA
authors.lastname: Yeramilli
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Knight
mesh_terms: D000818:Animals; D053264:B-Cell Activating Factor / Q000276:immunology / Q000378:metabolism; D016175:B-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D001483:Base Sequence; D051927:CD24 Antigen / Q000276:immunology / Q000378:metabolism; D002454:Cell Differentiation / Q000276:immunology; D049109:Cell Proliferation; D005434:Flow Cytometry; D041981:Gastrointestinal Tract / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D006706:Homeostasis / Q000276:immunology*; D006801:Humans; D008221:Lymphoid Tissue / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D054448:Precursor Cells, B-Lymphoid / Q000276:immunology* / Q000378:metabolism; D011817:Rabbits; D017464:Receptors, Complement 3d / Q000276:immunology / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid; D013997:Time Factors
chemical_list: D053264:B-Cell Activating Factor; D051927:CD24 Antigen; D017464:Receptors, Complement 3d