title: Memory B cells without somatic hypermutation are generated from Bcl6-deficient B cells.
abstract: After immunization with T cell-dependent antigens, the high-affinity B cells selected in germinal centers differentiate into memory B cells or long-lived antibody-forming cells. However, a role for germinal centers in development of these B lineage cells is still controversial. We show here that Bcl6-deficient B cells, which cannot develop germinal centers, differentiated into IgM and IgG1 memory B cells in the spleen but barely differentiated into long-lived IgG1 antibody-forming cells in the bone marrow. Mutation in the V-heavy gene was null in these memory B cells. Therefore, Bcl6 and germinal center formation are essential for somatic hypermutation, and generation of memory B cells can occur independently of germinal center formation, somatic hypermutation, and Ig class switching.
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D016175:B-Lymphocyte Subsets / Q000276:immunology*; D001853:Bone Marrow / Q000276:immunology; D001854:Bone Marrow Cells / Q000166:cytology / Q000276:immunology; D002454:Cell Differentiation; D019070:Cell Lineage; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D015326:Gene Rearrangement, B-Lymphocyte, Heavy Chain; D005803:Genes, Immunoglobulin; D018858:Germinal Center / Q000166:cytology / Q000276:immunology; D018398:Homeodomain Proteins / Q000235:genetics; D007114:Immunization; D017578:Immunoglobulin Class Switching; D007074:Immunoglobulin G / Q000096:biosynthesis; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007075:Immunoglobulin M / Q000096:biosynthesis; D007135:Immunoglobulin Variable Region / Q000235:genetics; D007156:Immunologic Memory / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009928:Organ Specificity; D011518:Proto-Oncogene Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D051560:Proto-Oncogene Proteins c-bcl-6; D011828:Radiation Chimera; D027041:Somatic Hypermutation, Immunoglobulin; D013047:Specific Pathogen-Free Organisms; D013154:Spleen / Q000166:cytology / Q000276:immunology; D014157:Transcription Factors / Q000172:deficiency / Q000235:genetics / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D007074:Immunoglobulin G; D007143:Immunoglobulin Heavy Chains; D007075:Immunoglobulin M; D007135:Immunoglobulin Variable Region; D011518:Proto-Oncogene Proteins; D051560:Proto-Oncogene Proteins c-bcl-6; D014157:Transcription Factors; C064658:RAG-1 protein