title: In vivo blockade of CD28/CTLA4: B7/BB1 interaction with CTLA4-Ig reduces lethal murine graft-versus-host disease across the major histocompatibility complex barrier in mice.
abstract: We tested whether the in vivo infusion of recombinant, soluble CTLA4 fused with Ig heavy chains, as a surrogate ligand used to block CD28/CTLA4 T-cell costimulation, could prevent efficient T-cell activation and thereby reduce graft-versus-host disease (GVHD). Lethally irradiated B10.BR recipients of major histocompatibility complex disparate C57BL/6 donor grafts received intraperitoneal injections of human CTLA4-Ig (hCTLA4-Ig) or murine CTLA4-Ig (mCTLA4-Ig) in various doses and schedules beginning on day -1 or day 0 of bone marrow transplantation (BMT). In all five experiments, recipients of CTLA4-Ig had a significantly higher actuarial survival rate compared to mice injected with an irrelevant antibody control (L6) or saline alone. Survival rates in recipients of hL6 or PBS were 0% at 29 to 45 days post-BMT. In recipients of CTLA4-Ig, survival rates were as high as 63% mice surviving 3 months post-BMT. However, protection was somewhat variable and recipients of CTLA4-Ig were not GVHD-free by body weight, clinical appearance, and histopathologic examination. There were no significant differences in the survival rates in comparing injection dose, injection duration, or species of CTLA4-Ig (hCTLA4-Ig v mCTLA4-Ig). Splenic and peripheral blood flow cytometry studies of long-term hCTLA4-Ig-injected survivors showed a significant peripheral B-cell and CD4+ T-cell lymphopenia, consistent with GVHD. A kinetic study of splenic reconstitution was performed in mice that received hCTLA4-Ig and showed that mature splenic localized CD8+ T-cell repopulation was not significantly different in recipients of hCTLA4-Ig compared with hL6, despite the significant increase in actuarial survival rate in that experiment. These data suggest that the beneficial effect of hCTLA4-Ig on survival is not mediated by interfering with mature donor-derived T-cell repopulation post-BMT. Neither hCTLA4-Ig nor mCTLA4-Ig interfered with hematopoietic recovery post-BMT. We conclude that CTLA4-Ig (most likely in combination with other agents) may represent an important new modality for GVHD prevention.
authors.affiliation: Department of Pediatrics, University of Minnesota Hospital and Clinic, Minneapolis.
authors.forename: B R
authors.initials: BR
authors.lastname: Blazar
authors.forename: P A
authors.initials: PA
authors.lastname: Taylor
authors.forename: P S
authors.initials: PS
authors.lastname: Linsley
authors.forename: D A
authors.initials: DA
authors.lastname: Vallera
mesh_terms: D000069594:Abatacept; D000818:Animals; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000008:administration & dosage / Q000627:therapeutic use*; D018122:B7-1 Antigen / Q000502:physiology*; D018106:CD28 Antigens / Q000502:physiology*; D060908:CTLA-4 Antigen; D005260:Female; D006086:Graft vs Host Disease / Q000517:prevention & control*; D006801:Humans; D018796:Immunoconjugates; D008285:Major Histocompatibility Complex; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D018122:B7-1 Antigen; D018106:CD28 Antigens; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; C556707:Ctla4 protein, mouse; D018796:Immunoconjugates; D000069594:Abatacept