Fas ligand enhances hematopoietic cell engraftment through abrogation of alloimmune responses and nonimmunogenic interactions

Michal Pearl-Yafe, Esma S. Yolcu, Jerry Stein, Ofer Kaplan, Isaac Yaniv, Haval Shirwan, Nadir Askenasy*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Early after transplantation, donor lineage-negative bone marrow cells (lin- BMC) constitutively upregulated their expression of Fas ligand (FasL), suggesting an involvement of the Fas/FasL axis in engraftment. Following the observation of impaired engraftment in the presence of a dysfunctional Fas/FasL axis in FasL-defective (gld) donors or Fas-defective (lpr) recipients, we expressed a noncleavable FasL chimeric protein on the surface of donor lin- BMC. Despite a short life span of the protein in vivo, expression of FasL on the surface of all the donor lin- BMC improved the efficiency of engraftment twofold. The FasL-coated donor cells efficiently blunted the host alloimmune responses in primary recipients and retained their hematopoietic reconstituting potential in secondary transplants. Surprisingly, FasL protein improved the efficiency of engraftment in syngeneic transplants. The deficient engraftment in lpr recipients was not reversed in chimeric mice with Fas- stroma and Fas+ BMC, demonstrating that the host marrow stroma was also a target of donor cell FasL. Hematopoietic stem and progenitor cells are insensitive to Fas-mediated apoptosis and thus can exploit the constitutive expression of FasL to exert potent veto activities in the early stages of engraftment. Manipulation of the donor cells using ectopic FasL protein accentuated the immunogenic and nonimmunogenic interactions between the donor cells and the host, alleviating the requirement for a megadose of transplanted cells to achieve a potent veto effect.

Original languageEnglish
Pages (from-to)1448-1455
Number of pages8
JournalStem Cells
Issue number6
StatePublished - Jun 2007
Externally publishedYes


  • Adult stem cells
  • Apoptosis
  • Fas
  • Hematopoietic stem cell transplantation


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