title: Synergistic tolerance induced by LF15-0195 and anti-CD45RB monoclonal antibody through suppressive dendritic cells.
abstract: BACKGROUND
  LF 15-0195 (LF), a novel analogue of 15-deoxyspergualin (DSG), inhibits maturation of dendritic cells (DC). Anti-CD45RB is a monoclonal antibody (mAb) that blocks activation of T-helper (Th) 1 cells and generates T-regulatory cells. This study addressed whether these two reagents act synergistically to inducing tolerance, and investigated associated cellular mechanisms.
  
  
  METHODS
  BALB/c recipients were treated by a short course of mAb alone, LF alone, or the combination of both agents. Mice that accepted a C57BL/6 cardiac allograft for more than 100 days were considered tolerant. Splenic DC were purified using positive selection for CD11c. Bone marrow DC were generated by culture with interleukin-4 and granulocyte-macrophage colony-stimulating factor. Surface marker expression was determined by fluorescence-activated cell sorter analysis. DC function was assessed by the ability to stimulate or inhibit T cells in vitro.
  
  
  RESULTS
  Although monotherapy with LF or mAb failed to induce tolerance, combination therapy resulted in long-lasting acceptance of allogeneic hearts (>200 days) and secondary donor skin grafts (>100 days). DC from tolerant recipients possessed lower major histocompatibility complex class II and CD40 expression, and were poorer co-stimulators for T-cell proliferation than control DC. Furthermore, DC from tolerant mice induced Th2 differentiation, suppressed overall T-cell proliferation, and were poor presenters of T cells specific for antigen to pigeon cytochrome c 81-104.
  
  
  CONCLUSIONS
  The combination of LF and anti-CD45RB mAb induced stable tolerance. The synergy of these two approaches appears to be mediated through formation of tolerogenic DC and T-regulatory cells.
authors.affiliation: Department of Surgery, University of Western Ontario, London, Ontario, Canada. mweiping@uwo.ca.
authors.forename: Wei-Ping
authors.initials: WP
authors.lastname: Min
authors.forename: Dejun
authors.initials: D
authors.lastname: Zhou
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Ichim
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Xia
authors.forename: Xiao
authors.initials: X
authors.lastname: Zhang
authors.forename: Jinming
authors.initials: J
authors.lastname: Yang
authors.forename: Xuyan
authors.initials: X
authors.lastname: Huang
authors.forename: Bertha
authors.initials: B
authors.lastname: Garcia
authors.forename: Patrick
authors.initials: P
authors.lastname: Dutartre
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Jevnikar
authors.forename: Gill H
authors.initials: GH
authors.lastname: Strejan
authors.forename: Robert
authors.initials: R
authors.lastname: Zhong
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D001854:Bone Marrow Cells / Q000187:drug effects / Q000502:physiology; D016764:Cell Polarity / Q000502:physiology; D003713:Dendritic Cells / Q000187:drug effects* / Q000502:physiology; D004357:Drug Synergism; D006146:Guanidines / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects; D016027:Heart Transplantation; D017493:Leukocyte Common Antigens / Q000276:immunology*; D007959:Lymphocyte Culture Test, Mixed; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D010641:Phenotype; D013154:Spleen / Q000473:pathology; D013601:T-Lymphocytes / Q000502:physiology; D006377:T-Lymphocytes, Helper-Inducer / Q000502:physiology; D023001:Transplantation Tolerance; D016042:Transplantation, Heterotopic; D014184:Transplantation, Homologous
chemical_list: D000911:Antibodies, Monoclonal; D006146:Guanidines; C434185:LF 150195; D017493:Leukocyte Common Antigens