The overall objective of this proposal is to study clinical approaches, based on strategies that are derived from our developmental laboratory and clinical studies, for improving the outcome of bone marrow transplantation (BMT). Clinical studies under development in other projects of this grant or in independently funded grants will not be included in this project. Specifically, we plan to: a. Utilize graft engineering methodology to overcome the major complications of T-cell depletion for prophylaxis of graft-host disease (GVHD): graft failure and relapse. b. Investigate clinical approaches for improving the antitumor activity associated with BMT. c. Study the efficacy of purging in autologous BMT. d. Improve the supportive care of the BMT patient with regard to the prevention of hemorrhagic cystitis and pneumocystis pneumonia.