title: Ectopic expression of B7-1 (CD80) on T lymphocytes in autoimmune lpr and gld mice.
abstract: Defective Fas-mediated apoptosis in mice, caused by the gld mutation in the fas ligand gene, results in the development of lupus-like autoantibodies and severe lymphoproliferation. We previously demonstrated ectopic expression of the costimulatory molecule B7-1 (CD80) on T lymphocytes in B6/gld mice. This report extends these observations by demonstrating similar results in B6/lpr mice, which possess a mutation in the gene encoding Fas. Additionally, we demonstrate that this phenomenon is age-dependent and occurs on multiple subsets of B6/gld T lymphocytes. B7-1 upregulation is observed on T cells from both conventionally housed and specific-pathogen-free B6/gld mice, suggesting that this is not a consequence of infection by pathogen. T cells from lpr and gld mice show increased binding of CTLA4-Ig fusion protein, suggesting that the upregulated B7-1 is functional. CD28, a receptor for B7-1 which activates T cells, is upregulated in B6/lpr and B6/gld mice, while CTLA4, a negative regulator of T cells which binds B7-1, is not. Our results suggest that ectopic expression of B7-1 on T cells of lpr and gld mice may be playing a role in exacerbation of lymphoproliferation and/or autoimmunity.
authors.affiliation: Department of Medicine, University of North Carolina, Chapel Hill 27599-7280, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Weintraub
authors.forename: P L
authors.initials: PL
authors.lastname: Cohen
mesh_terms: D000069594:Abatacept; D000818:Animals; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000378:metabolism; D001327:Autoimmune Diseases / Q000235:genetics* / Q000276:immunology*; D015551:Autoimmunity; D018122:B7-1 Antigen / Q000378:metabolism*; D018106:CD28 Antigens / Q000378:metabolism; D060908:CTLA-4 Antigen; D053222:Fas Ligand Protein; D018796:Immunoconjugates; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D019463:Mice, Inbred MRL lpr; D008817:Mice, Mutant Strains; D013601:T-Lymphocytes / Q000276:immunology*; D015854:Up-Regulation
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D018122:B7-1 Antigen; D018106:CD28 Antigens; D060908:CTLA-4 Antigen; C556707:Ctla4 protein, mouse; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D018796:Immunoconjugates; D008562:Membrane Glycoproteins; D000069594:Abatacept