OBJECTIVES: I. Determine if patients with refractory, high risk hematologic malignancies or bone marrow failure who receive HLA haploidentical bone marrow treated with anti-B7 antibody have normal engraftment. II. Determine if these patients are free of hyperacute graft versus host disease (GVHD), defined as grade D GVHD in the first 10 posttransplant days, when treated with this regimen. III. Determine if these patients have an acceptable incidence of life threatening grade D GHVD in the first 50 posttransplant days following this treatment regimen. IV. Determine the safety and tolerability of this treatment regimen in this patient population.