Blockade of the CD40/CD154 pathway enhances T-cell-depleted allogeneic bone marrow engraftment under nonmyeloablative and irradiation-free conditioning therapy.

Background: T-cell-depleted bone marrow transplantation (TDBMT) can prevent graft-versus-host disease (GvHD). However, depleting T cells from allogeneic bone marrow often results in failure of bone marrow engraftment under irradiation conditioning. It is not know whether donor T cells are essential for bone marrow engraftment and whether blocking the CD40/CD154 pathway promotes allogeneic TDBM engraftment under nonmyeloablative and irradiation-free fludarabine phosphate and cyclophosphamide conditioning therapy.