title: Induction of immunologic tolerance to cardiac allograft by simultaneous blockade of inducible co-stimulator and cytotoxic T-lymphocyte antigen 4 pathway.
abstract: BACKGROUND
  Inducible co-stimulator (ICOS) is one of the most recently described members of the CD28 family, and it plays an important role in immune responses. To investigate the role of ICOS in allograft rejection, the authors studied graft survival after cardiac transplantation in mice.
  
  
  METHODS
  Hearts from BALB/c mice were transplanted into C3H/He mice. Immunohistochemical staining and flow cytometry were performed. Monoclonal antibody to ICOS or ICOS-immunoglobulin (Ig) was injected intraperitoneally. The authors performed mixed lymphocyte reaction (MLR).
  
  
  RESULTS
  ICOS was expressed strongly by graft-infiltrating cells during rejection of the allograft. Blockade of the ICOS pathway with anti-ICOS antibody and ICOSIg significantly prolonged graft survival time relative to that in untreated mice; however, all cardiac allografts were eventually rejected by a single treatment. Treatment with both ICOSIg and cytotoxic T-lymphocyte antigen 4 (CTLA4) Ig induced not only long-term acceptance of the cardiac allograft but also donor-specific tolerance, which was shown by acceptance of donor but not third-party skin. Graft arterial intimal hyperplasia in these cardiac allografts was remarkably less than that in cardiac allografts treated with tacrolimus. Addition of anti-ICOS antibody or ICOSIg to MLR resulted in inhibition of T-cell proliferation.
  
  
  CONCLUSIONS
  Inhibition of T-cell proliferation with ICOSIg and CTLA4Ig was more effective than that with ICOSIg alone. Thus, ICOS appears to be an important regulator of T-cell activation, and may be an effective therapy in clinical cardiac transplantation.
authors.affiliation: Department of Cardiovascular Medicine, Tokyo Medical and Dental University, Yushima, Bunkyo-ku, Tokyo, Japan.
authors.forename: Hisanori
authors.initials: H
authors.lastname: Kosuge
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Suzuki
authors.forename: Ryo
authors.initials: R
authors.lastname: Gotoh
authors.forename: Noritaka
authors.initials: N
authors.lastname: Koga
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ito
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Isobe
authors.forename: Manabu
authors.initials: M
authors.lastname: Inobe
authors.forename: Toshimitsu
authors.initials: T
authors.lastname: Uede
mesh_terms: D000069594:Abatacept; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000276:immunology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology* / Q000378:metabolism; D060908:CTLA-4 Antigen; D006085:Graft Survival / Q000187:drug effects; D016027:Heart Transplantation / Q000276:immunology*; D018796:Immunoconjugates; D007136:Immunoglobulins / Q000494:pharmacology*; D060889:Inducible T-Cell Co-Stimulator Protein; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D011184:Postoperative Period; D013997:Time Factors; D014019:Tissue Donors; D023001:Transplantation Tolerance; D014184:Transplantation, Homologous
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000943:Antigens, Differentiation; D000945:Antigens, Differentiation, T-Lymphocyte; D060908:CTLA-4 Antigen; C556707:Ctla4 protein, mouse; C556694:Icos protein, mouse; D018796:Immunoconjugates; D007136:Immunoglobulins; D060889:Inducible T-Cell Co-Stimulator Protein; D000069594:Abatacept