title: IL-6 contributes to the expression of RAGs in human mature B cells.
abstract: Mature B cells acquire the capacity to revise rearranged Ig V region genes in secondary lymphoid organs. In previous studies, we demonstrated that cross-linking the BCR and the CD40 induces the expression of the RAG1 and RAG2 enzymes and, thereby, secondary rearrangements. We examine herein the mechanism that underpins RAG1 and RAG2 expression in peripheral and tonsil B cells. Coordinated engagement of the BCR and CD40 promoted the synthesis of IL-6 and, thereby, up-regulation of its receptor on activated B lymphocytes. Furthermore, we provide evidence that IL-6 initiates the expression of RAGs in circulating B cells, and extends those in tonsil B cells. Thus, neutralization of IL-6 or blocking of its receptor inhibits RAG expression. Moreover, we demonstrate that IL-6 impedes BCR-mediated termination of RAG gene expression in both population of B cells. The recovered inhibition of RAG gene transcription by IL-6 receptor blockade supports the notion that once recombination is launched, its termination is also regulated by IL-6. Taken together, these studies provide new insight into the dual role of IL-6 in inducing and terminating expression of the recombinase machinery for secondary rearrangements in mature human B cells.
authors.affiliation: Laboratory of Immunology, Brest University Medical School Hospital, Brest, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Hillion
authors.forename: Maryvonne
authors.initials: M
authors.lastname: Dueymes
authors.forename: Pierre
authors.initials: P
authors.lastname: Youinou
authors.forename: Christophe
authors.initials: C
authors.lastname: Jamin
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000201:enzymology / Q000276:immunology*; D019013:CD40 Antigens / Q000276:immunology; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000276:immunology*; D015322:Gene Rearrangement, B-Lymphocyte / Q000276:immunology*; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000276:immunology*; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000276:immunology; D015850:Interleukin-6 / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000276:immunology*; D014066:Palatine Tonsil / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D011940:Receptor Aggregation / Q000276:immunology; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism; D012756:Sheep; D015854:Up-Regulation / Q000276:immunology*; D000093242:Interleukin-6 Inhibitors
chemical_list: D019013:CD40 Antigens; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D007135:Immunoglobulin Variable Region; D015850:Interleukin-6; D009687:Nuclear Proteins; D011947:Receptors, Antigen, B-Cell; D000093242:Interleukin-6 Inhibitors; C508600:IL6 protein, human; C499311:RAG2 protein, human; C064658:RAG-1 protein