title: Natural occurrence and origin of somatically mutated memory B cells in mice.
abstract: While most murine peripheral B cells express germline-encoded antibodies of classes M and D (mu+ delta+ cells), small numbers of memory B cells expressing somatically mutated immunoglobulin G antibodies are generated upon T cell-dependent immunization. Analyzing the antibody repertoire of the mu-delta- B cell pool in unimmunized mice, we show that these cells express somatically mutated VH genes and that most of these genes derive from a set of germline VH genes dominantly expressed by mu+delta+ B cells. Thus, class-switched memory B cells are generated in the absence of intentional immunization, presumably in response to environmental antigens. These cells are either recruited from mu+delta+ B cells or selected from newly arising B cells in parallel to the latter, by the same antigens.
authors.affiliation: Institute for Genetics, University of Cologne, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Schittek
authors.forename: K
authors.initials: K
authors.lastname: Rajewsky
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000235:genetics / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D001483:Base Sequence; D002999:Clone Cells; D004247:DNA; D005260:Female; D005434:Flow Cytometry; D007135:Immunoglobulin Variable Region / Q000235:genetics / Q000276:immunology; D007156:Immunologic Memory / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009154:Mutation; D016415:Sequence Alignment
chemical_list: D000906:Antibodies; D007135:Immunoglobulin Variable Region; D004247:DNA