Bone marrow transplantation across major histocompatibility barriers in mice. Effect of elimination of T cells from donor grafts by treatment with monoclonal Thy-1.2 plus complement or antibody alone.

The current studies were designed to evaluated optimal conditions for reduction of graft-versus-host disease (GVHD) by removal of donor T cells from bone marrow inoculum. A model was used in which the addition of spleen cells to donor marrow heavily favored the development of lethal GVHD. Treatment of donor bone marrow plus spleen cells with monoclonal anti-Thy-1.2 antibody plus complement protected lethally irradiated recipients from GVHD across major histocompatibility barriers better than donor cells treated with the same dilution of antibody alone. Engraftment was demonstrated by the presence of high percentages of donor cells in the peripheral blood of these animals and the long-term survival of donor skin grafts. These results may be important in light of the development of new antihuman T cell monoclonal antibodies which may be used in the treatment of donor marrow in clinical transplantation.