TRANSPLANTATION BY CYTOLYTIC-DEFICIENT BONE MARROW

Project: Research project

Project Details

Description

Several approaches aimed at the induction of donor specific tolerance in
recipients of organ and tissue grafts have been explored in the past.
Amongst these, the administration of donor-specific bone marrow (BM) (prior
to or together with organ transplants) has yielded encouraging results in
small animal experimental models. One of the major drawbacks of such
strategy, especially when radiation conditioning of the recipient is used,
is represented by the risk of development of graft-versus-host disease
(GVHD), which is thought to be mediated by the activation of donor-derived,
recipient-specific, cytotoxic T lymphocytes. The removal of T cells from
the BM inoculum before transplantation is indeed characterized by reduced
incidence of GVHD, but also by reduced rate of engraftment. Cell mediated
cytolysis occurs via at least two pathways; one dependent on the release of
a lytic protein,named perforin, from cytotoxic cells, the other dependent
on contact of a surface protein, named Fas ligand, expressed on the surface
of cytotoxic effectors, with the Fas protein (also called Fas receptor or
APO-1) on the surface of target cells.

It is the purpose of this proposal to evaluate the use of BM cells derived
from donors that have impaired or deficient cell-mediated cytotoxic
functions, in BM transplantation aimed at inducing donor specific tolerance
to subsequent tissues and organ grafts.

The availability of mice lacking either a functional perforin (perforin
knock out) or a functional Fas pathway (gld/gld mice) will allow us to
evaluate in detail the role of these cytotoxicity-mediating pathways in the
establishment of engraftment, the induction of chimerism and donor specific
tolerance in allogeneic and xenogeneic models of BM transplantation, as
well as in the development of GVHD.

We have encouraging preliminary data that suggest an important role of
perforin in the induction of GVHD. Lethally irradiated allogeneic
recipients, when transplanted with wild type BM, invariably develop lethal
GVHD. When they receive BM from perforin knock out donors, full allogeneic
reconstitution occurs, donor specific tolerance is achieved and no GVHD is
observed. The addition of high T cell inocula from perforin KO donors, on
the other hand, is accompanied by development of GVHD, although
characterized by a delayed onset and a slower course. This implies a
possible role for other pathways of cytotoxicity in GVHD development, and
sets the rationale for the proposed studies that will also use Fas-ligand
deficient donors, as well as double deficient (perforin and Fas ligand)
donors.

Specifically, we intend to examine: the role of perforin and Fas pathways
in BM recipient reconstitution, chimerism establishment and donor-specific
tolerance induction. Furthermore, we intend to evaluate the immune profile
of successfully reconstituted allogeneic or xenogeneic chimeras. The
knowledge gained on chimerism establishment tolerance induction and
prevention of GVHD by utilizing cytotoxically deficient donors will help
not only in understanding the basic mechanisms of these phenomena, but
might also help in evaluating the potential use of similar protocols in
large animals models, with the ultimate goal of transferring this approach
to the clinical setting.
StatusFinished
Effective start/end date8/9/967/31/00

Funding

  • National Institute of Diabetes and Digestive and Kidney Diseases
  • National Institute of Diabetes and Digestive and Kidney Diseases
  • National Institute of Diabetes and Digestive and Kidney Diseases

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