title: Reversing Tolerance in Isotype Switch-Competent Anti-Insulin B Lymphocytes.
abstract: Autoreactive B lymphocytes that escape central tolerance and mature in the periphery are a liability for developing autoimmunity. IgG insulin autoantibodies that predict type 1 diabetes and complicate insulin therapies indicate that mechanisms for tolerance to insulin are flawed. To examine peripheral tolerance in anti-insulin B cells, we generated C57BL/6 mice that harbor anti-insulin VDJH-125 site directed to the native IgH locus (VH125(SD)). Class switch-competent anti-insulin B cells fail to produce IgG Abs following T cell-dependent immunization of VH125(SD) mice with heterologous insulin, and they exhibit markedly impaired proliferation to anti-CD40 plus insulin in vitro. In contrast, costimulation with LPS plus insulin drives robust anti-insulin B cell proliferation. Furthermore, VH125(SD) mice produce both IgM and IgG2a anti-insulin Abs following immunization with insulin conjugated to type 1 T cell-independent Brucella abortus ring test Ag (BRT). Anti-insulin B cells undergo clonal expansion in vivo and emerge as IgM(+) and IgM(-) GL7(+)Fas(+) germinal center (GC) B cells following immunization with insulin-BRT, but not BRT alone. Analysis of Igκ genes in VH125(SD) mice immunized with insulin-BRT reveals that anti-insulin Vκ from the preimmune repertoire is selected into GCs. These data demonstrate that class switch-competent anti-insulin B cells remain functionally silent in T cell-dependent immune responses, yet these B cells are vulnerable to reversal of anergy following combined BCR/TLR engagement that promotes Ag-specific GC responses and Ab production. Environmental factors that lead to infection and inflammation could play a critical yet underappreciated role in driving loss of tolerance and promoting autoimmune disease.
authors.affiliation: Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN 37232; and Division of Rheumatology and Immunology, Department of Medicine, Vanderbilt University, Nashville, TN 37232.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Williams
authors.affiliation: Division of Rheumatology and Immunology, Department of Medicine, Vanderbilt University, Nashville, TN 37232.
authors.forename: Rachel H
authors.initials: RH
authors.lastname: Bonami
authors.affiliation: Division of Rheumatology and Immunology, Department of Medicine, Vanderbilt University, Nashville, TN 37232.
authors.forename: Chrys
authors.initials: C
authors.lastname: Hulbert
authors.affiliation: Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN 37232; and Division of Rheumatology and Immunology, Department of Medicine, Vanderbilt University, Nashville, TN 37232 james.w.thomas@vanderbilt.edu.
authors.forename: James W
authors.initials: JW
authors.lastname: Thomas
mesh_terms: D000818:Animals; D001323:Autoantibodies / Q000096:biosynthesis / Q000276:immunology*; D015551:Autoimmunity / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D019013:CD40 Antigens / Q000276:immunology; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics / Q000276:immunology*; D007108:Immune Tolerance / Q000276:immunology; D007074:Immunoglobulin G / Q000096:biosynthesis / Q000276:immunology; D007075:Immunoglobulin M / Q000096:biosynthesis / Q000276:immunology; D007328:Insulin / Q000276:immunology*; D007330:Insulin Antibodies / Q000276:immunology*; D008070:Lipopolysaccharides; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D050441:VDJ Exons / Q000276:immunology
chemical_list: D001323:Autoantibodies; D019013:CD40 Antigens; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007328:Insulin; D007330:Insulin Antibodies; D008070:Lipopolysaccharides