title: Antigen-independent appearance of recombination activating gene (RAG)-positive bone marrow B cells in the spleens of immunized mice.
abstract: Splenic B lineage cells expressing recombination activation genes (RAG(+)) in mice immunized with 4-hydroxy-3-nitrophenyl-acetyl coupled to chicken gamma-globulin (NP-CGG) and the adjuvant aluminum-hydroxide (alum) have been proposed to be mature B cells that reexpress RAG after an antigen encounter in the germinal center (GC), a notion supported by findings of RAG expression in peripheral B lymphocyte populations activated in vitro. However, recent studies indicate that these cells might be immature B cells that have not yet extinguished RAG expression. Here, we employ RAG2-green fluorescent protein (GFP) fusion gene knock-in mice to show that RAG(+) B lineage cells do appear in the spleen after the administration of alum alone, and that their appearance is independent of T cell interactions via the CD40 pathway. Moreover, splenic RAG(+) B lineage cells were detectable in immunized RAG2-deficient mice adoptively transferred with bone marrow (BM) cells, but not with spleen cells from RAG(+) mice. Although splenic RAG(+) B cells express surface markers associated with GC B cells, we also find the same basic markers on progenitor/precursor BM B cells. Finally, we did not detect RAG gene expression after the in vitro stimulation of splenic RAG(-) mature B cells with mitogens (lipopolysaccharide and anti-CD40) and cytokines (interleukin [IL]-4 and IL-7). Together, our studies indicate that RAG(+) B lineage cells from BM accumulate in the spleen after immunization, and that this accumulation is not the result of an antigen-specific response.
authors: The Howard Hughes Medical Institute, the Children's Hospital, the Center for Blood Research, and the Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors: F
authors: F
authors: Gärtner
authors: F W
authors: FW
authors: Alt
authors: R J
authors: RJ
authors: Monroe
authors: K J
authors: KJ
authors: Seidl
mesh_terms: D019264:Adoptive Transfer; D000534:Alum Compounds; D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism / Q000637:transplantation; D001854:Bone Marrow Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D016026:Bone Marrow Transplantation; D019013:CD40 Antigens / Q000276:immunology; D019070:Cell Lineage; D002478:Cells, Cultured; D002634:Chemotaxis, Leukocyte; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005434:Flow Cytometry; D016654:Genes, RAG-1 / Q000235:genetics*; D007114:Immunization; D008213:Lymphocyte Activation; D051379:Mice; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D011993:Recombinant Fusion Proteins; D013154:Spleen / Q000166:cytology / Q000276:immunology*; D005719:gamma-Globulins / Q000276:immunology
chemical_list: D000534:Alum Compounds; D019013:CD40 Antigens; D004268:DNA-Binding Proteins; C499308:Rag2 protein, mouse; D011993:Recombinant Fusion Proteins; C064655:V(D)J recombination activating protein 2; D005719:gamma-Globulins; C041524:aluminum sulfate