title: Follicular exclusion and rapid elimination of hen egg lysozyme autoantigen-binding B cells are dependent on competitor B cells, but not on T cells.
abstract: In mice with a diverse B cell repertoire, hen egg lysozyme (HEL) autoantigen-binding B cells are excluded from follicles and eliminated in 3 days. To explore the roles of competitor B cells and of T cells in this mechanism of self-tolerance, HEL-specific B cells were transferred into mice containing HEL and deficient in endogenous B cells (muMT), T cells (TCR-/-), or B and T cells (RAG1-/-). Previous studies suggested a dual requirement for B cell receptor (BCR) engagement and competition in HEL autoantigen-binding B cell elimination, but interpretation of these experiments has been confounded by the possible failure to independently regulate autoantigen concentration and competitor B cell frequency. In experiments in this study, we have fixed one variable, HEL concentration, while varying the second, the presence or absence of other B cells. By this approach, we find that follicular exclusion and rapid elimination of autoreactive B cells require BCR engagement plus competition with other B cells, rather than BCR engagement alone. We also find, by transfers into T cell-deficient mice, that T cells are not required for this peripheral tolerance mechanism. Unexpectedly, in mice lacking both T cells and competitor B cells (RAG1-/-), transferred HEL-binding cells survive less well than in mice just lacking competitor B cells. These results suggest T cells can enhance autoreactive B cell survival. Enhanced survival of autoreactive B cells, due to the presence of T cells and the lack of competitor B cells, might contribute to the elevated frequency of autoimmunity in B cell-deficient individuals.
authors.affiliation: Department of Microbiology and Immunology, University of California, San Francisco 94143, USA.
authors.forename: K N
authors.initials: KN
authors.lastname: Schmidt
authors.forename: J G
authors.initials: JG
authors.lastname: Cyster
mesh_terms: D000818:Animals; D001324:Autoantigens / Q000378:metabolism*; D016175:B-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D001667:Binding, Competitive / Q000276:immunology; D002465:Cell Movement / Q000276:immunology*; D002470:Cell Survival / Q000276:immunology; D002645:Chickens; D008221:Lymphoid Tissue / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D008231:Lymphopenia / Q000235:genetics / Q000276:immunology / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009113:Muramidase / Q000276:immunology* / Q000378:metabolism; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism
chemical_list: D001324:Autoantigens; D009113:Muramidase