Sustained recovery of hematopoiesis and immunity following transplantation of fetal liver cells in dogs.

We studied the ability of fetal liver cells to reconstitute hematopoiesis and immunity in lethally irradiated dogs. Engraftment and sustained lymphoid and hematopoietic recovery was achieved when the recipients received a preparative regime of high-dose total body irradiation (TBI) alone followed by transplantation of DLA-identical fetal liver. The combination of high-dose TBI and cyclosporine allowed engraftment in DLA-mismatched fetal liver transplants. Typical features of graft-versus-host disease (GvHD) did not occur although autoimmune-like syndromes (myasthenia gravis, immune thrombocytopenia) were observed in some recipients. Hematopoietic recovery was rapid and complete. Recovery of T- and B-lymphocyte function was comparatively delayed, but sufficient to prevent opportunistic infections after the initial 3 months post transplant. These data indicate that cells from a single fetal liver can reconstitute hematopoiesis and immunity in DLA-mismatched recipients and suggest that human fetal liver cell transplantation may be an effective source of stem cells for patients who lack an HLA-identical donor for bone marrow transplantation.