title: CD28/B7 regulation of anti-CD3-mediated immunosuppression in vivo.
abstract: FcR-binding "classical" anti-CD3 mAb is a potent immunosuppressive drug that alters CD4(+) and CD8(+) T cell function in vivo via anergy induction and programmed cell death (PCD). Anti-CD3-mediated PCD was Fas independent but was mediated by the mitochondria-initiated apoptosis that was abrogated in Bcl-x(L)-transgenic T cells. The PCD was more pronounced in CD28-deficient mice consistent with defective Bcl-x(L) up-regulation. Residual T cells isolated from anti-CD3-treated wild-type, CD28(-/-), and Bcl-x(L)-transgenic mice were hyporesponsive. The hyporesponsiveness was more pronounced in CD28(-/-) and wild-type mice treated with anti-B7-2, suggesting that CD28 interaction with B7-2 regulates T cell responsiveness in anti-CD3-treated animals. Finally, anti-CD3 treatment led to indefinite cardiac allograft survival in wild-type but not Bcl-x(L) animals. Together these results implicate CD28/B7 signaling in the regulation of both anti-CD3-induced T cell depletion and hyporesponsiveness in vivo, but T cell depletion, not hyporesponsiveness, appears to be critical for anti-CD3 mAb-mediated long-term immune regulation.
authors.affiliation: Diabetes Center and Department of Medicine, University of California, San Francisco, CA 94143, USA.
authors.forename: Qizhi
authors.initials: Q
authors.lastname: Tang
authors.forename: Judy A
authors.initials: JA
authors.lastname: Smith
authors.forename: Greg L
authors.initials: GL
authors.lastname: Szot
authors.forename: Ping
authors.initials: P
authors.lastname: Zhou
authors.forename: Maria-Luisa
authors.initials: ML
authors.lastname: Alegre
authors.forename: Kammi J
authors.initials: KJ
authors.lastname: Henriksen
authors.forename: Craig B
authors.initials: CB
authors.lastname: Thompson
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Bluestone
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage*; D015703:Antigens, CD / Q000378:metabolism; D017209:Apoptosis / Q000235:genetics / Q000276:immunology; D018122:B7-1 Antigen / Q000502:physiology*; D051940:B7-2 Antigen; D018106:CD28 Antigens / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017252:CD3 Complex / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D017635:Clonal Anergy / Q000235:genetics / Q000276:immunology; D006085:Graft Survival / Q000235:genetics / Q000276:immunology; D016027:Heart Transplantation / Q000276:immunology / Q000473:pathology; D007166:Immunosuppressive Agents / Q000008:administration & dosage*; D008212:Lymphocyte Depletion; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics; D051020:bcl-X Protein; D019014:fas Receptor / Q000502:physiology
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D018122:B7-1 Antigen; D051940:B7-2 Antigen; C494812:Bcl2l1 protein, mouse; D018106:CD28 Antigens; D017252:CD3 Complex; C497965:Cd86 protein, mouse; D007166:Immunosuppressive Agents; D008562:Membrane Glycoproteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051020:bcl-X Protein; D019014:fas Receptor