title: In vitro and in vivo activation induces BAFF and APRIL expression in B cells.
abstract: B cell-activating factor (BAFF) and a proliferation-inducing ligand (APRIL) play key roles in peripheral B cell survival, maturation, and differentiation. BAFF and APRIL are produced by a variety of cell types such as macrophages/monocytes and dendritic cells. Our analysis shows that BAFF mRNA is also expressed in all B cell subsets isolated from bone marrow, spleen, and peritoneal cavity of BALB/c mice. APRIL expression is restricted to early stages of B cell development in the bone marrow and the peritoneal B1 subset. Stimulation of B2 and B1 cells with LPS or CpG-oligodeoxynucleotides induced MyD88-dependent plasma cell differentiation and intracellular expression of BAFF and APRIL. Furthermore, activation of B cells up-regulated membrane expression of BAFF. The finding that in vitro activation of B cells is inhibited by the antagonist transmembrane activator and calcium modulator ligand interactor Ig, indicates that BAFF and/or APRIL are released into the culture supernatants. It shows that B cell survival, proliferation, and differentiation are supported by an autocrine pathway. In vivo activation of B cells with a T-dependent Ag- induced BAFF expression in germinal center B cells. In (NZB x NZW)F(1) mice with established autoimmune disease, marginal zone, germinal center B cells, as well as splenic plasma cells expressed high levels of BAFF. In (NZB x NZW)F(1) mice, the continuous activation of B cells and thus overexpression of BAFF and APRIL may contribute to the development of autoimmune disease.
authors.affiliation: Deutsches Rheuma ForschungsZentrum, Berlin, Germany.
authors.forename: Van Trung
authors.initials: VT
authors.lastname: Chu
authors.forename: Philipp
authors.initials: P
authors.lastname: Enghard
authors.forename: Gabriela
authors.initials: G
authors.lastname: Riemekasten
authors.forename: Claudia
authors.initials: C
authors.lastname: Berek
mesh_terms: D000818:Animals; D053264:B-Cell Activating Factor / Q000235:genetics / Q000378:metabolism*; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D008213:Lymphocyte Activation / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D012333:RNA, Messenger / Q000235:genetics; D053300:Tumor Necrosis Factor Ligand Superfamily Member 13 / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D053264:B-Cell Activating Factor; D012333:RNA, Messenger; C491959:Tnfsf13 protein, mouse; D053300:Tumor Necrosis Factor Ligand Superfamily Member 13