title: Mouse T cells engineered to display on their surface a novel form of FasL protein undergo apoptosis when stimulated with alloantigens: implications for graft-versus-host disease.
abstract: BACKGROUND
  Allogeneic bone marrow transplantation as a therapeutic approach in the clinic suffers from graft-versus- host disease (GVHD) initiated and perpetuated by donor T cells responding to alloantigens in immunocompromised hosts. Although the depletion of mature T cells from bone marrow inoculum overcomes GVHD, this manipulation is associated with engraftment failure and early post-transplant infection complications. Therefore, approaches that specifically purge out alloreactive T cells in the bone marrow inoculum without major effect on alloantigen-nonreactive T cells may be effective in facilitating engraftment without complications of GVHD and infections.
  
  
  METHODS
  Inasmuch as Fas/FasL-induced apoptosis plays a critical role in self-tolerance, we tested whether the direct display of a novel form of FasL (SA-FasL) protein chimeric with streptavidin (SA) on the surface of T cells induces apoptosis in such cells in response to alloantigens. BALB/c and C57BL/6 total lymphocytes or purified T cells were biotinylated under physiologic conditions and engineered with SA-FasL protein taking advantage of the high-affinity interaction between biotin and SA.
  
  
  RESULTS
  All engineered cells displayed SA-FasL protein on their surface as determined by flow cytometry. When used as responders against irradiated, unmodified allogeneic stimulators, the SA-FasL-engineered T cells underwent apoptosis, which resulted in minimal proliferation. This effect was specific to SA-FasL; control SA protein-engineered T cells generated a potent proliferative alloresponse without significant apoptosis.
  
  
  CONCLUSIONS
  Taken together, these results demonstrate the feasibility of purging out alloreactive T cells by the display of SA-FasL protein on their surface with important implications for the prevention of GVHD associated with allogeneic bone marrow transplantation.
authors.affiliation: Institute for Cellular Therapeutics and Department of Microbiology and Immunology, University of Louisville, Kentucky. esma.yolcu@louisville.edu
authors.forename: E S
authors.initials: ES
authors.lastname: Yolcu
authors.forename: N P
authors.initials: NP
authors.lastname: Singh
mesh_terms: D000818:Animals; D017209:Apoptosis; D053222:Fas Ligand Protein / Q000276:immunology*; D006086:Graft vs Host Disease / Q000276:immunology*; D007519:Isoantigens / Q000276:immunology*; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology
chemical_list: D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D007519:Isoantigens