title: New insights into the interactions between T-cell costimulatory blockade and conventional immunosuppressive drugs.
abstract: OBJECTIVE
  To determine the precise in vivo interaction between T-cell costimulatory blockade and conventional immunosuppression in transplantation.
  
  
  BACKGROUND
  Blocking B7 or CD154 T-cell costimulatory activation pathways prevents allograft rejection in small and large animal transplant models and is considered a promising strategy for clinical organ transplantation.
  
  
  METHODS
  A fully MHC-mismatched vascularized mouse cardiac allograft model was used to test the interactions between anti-CD154 or CTLA4Ig monotherapy and conventional immunosuppressive drugs in promoting long-term graft acceptance. The frequency of alloreactive T cell was measured by ELISPOT. Chronic rejection was examined by histology.
  
  
  RESULTS
  Cyclosporine, tacrolimus, and anti-IL-2R monoclonal antibody therapy abrogated the effect of a single-dose protocol of anti-CD154 therapy. In contrast, rapamycin acted synergistically with anti-CD154 therapy in promoting long-term allograft survival. The addition of calcineurin inhibitors did not abolish this synergistic effect. Intense CD154-CD40 blockade by a multiple-dose schedule of anti-CD154 resulted in long-term graft survival and profound alloreactive T-cell unresponsiveness and overcame the opposite effects of calcineurin inhibitors. CTLA4Ig induced long-term graft survival, and the effect was not affected by the concomitant use of any immunosuppressive drugs.
  
  
  CONCLUSIONS
  The widespread view that calcineurin inhibitors abrogate the effects of T-cell costimulatory blockade should be revisited. Sufficient costimulatory blockade and synergy induced by CD154 blockade and rapamycin promote allograft tolerance and prevent chronic rejection.
authors.affiliation: Laboratory of Immunogenetics and Transplantation, Brigham and Women's Hospital, Boston, Massachusetts, USA.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Sho
authors.forename: Sigrid E
authors.initials: SE
authors.lastname: Sandner
authors.forename: Nader
authors.initials: N
authors.lastname: Najafian
authors.forename: Alan D
authors.initials: AD
authors.lastname: Salama
authors.forename: Victor
authors.initials: V
authors.lastname: Dong
authors.forename: Akira
authors.initials: A
authors.lastname: Yamada
authors.forename: Koji
authors.initials: K
authors.lastname: Kishimoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Harada
authors.forename: Isabela
authors.initials: I
authors.lastname: Schmitt
authors.forename: Mohamed H
authors.initials: MH
authors.lastname: Sayegh
mesh_terms: D000069594:Abatacept; D000818:Animals; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000627:therapeutic use*; D023201:CD40 Ligand / Q000276:immunology*; D060908:CTLA-4 Antigen; D065095:Calcineurin Inhibitors; D016572:Cyclosporine / Q000494:pharmacology / Q000627:therapeutic use; D006084:Graft Rejection / Q000276:immunology / Q000517:prevention & control*; D016027:Heart Transplantation; D018796:Immunoconjugates; D007141:Immunoglobulin Fc Fragments / Q000627:therapeutic use*; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D008775:Methylprednisolone / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D020123:Sirolimus / Q000494:pharmacology / Q000627:therapeutic use; D013601:T-Lymphocytes / Q000276:immunology*; D016559:Tacrolimus / Q000494:pharmacology / Q000627:therapeutic use; D014184:Transplantation, Homologous
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000943:Antigens, Differentiation; D060908:CTLA-4 Antigen; D065095:Calcineurin Inhibitors; C556707:Ctla4 protein, mouse; D018796:Immunoconjugates; D007141:Immunoglobulin Fc Fragments; D007166:Immunosuppressive Agents; D023201:CD40 Ligand; D000069594:Abatacept; D016572:Cyclosporine; D020123:Sirolimus; D016559:Tacrolimus; D008775:Methylprednisolone