Successful use of multiagent immunosuppression in the bone marrow transplantation of sensitized patients.

Of 23 patients with severe aplastic anemia, 17 were sensitized to histocompatibility antigens of HLA-A, -B, and -D loci-identical potential sibling donors as determined by cell-mediated lysis (CML) assays in vitro. Antibody-dependent sensitization was detected in 3 patients, antibody-independent cellular sensitization in 11, and both in 3. Fourteen sensitized patients were transplanted after initial multiagent immunosuppression consisting of rabbit anti-human thymocyte serum, procarbazine, and cyclophosphamide, eleven with a CML-positive donor and three with a CML-negative donor. Engraftment was achieved in each of 13 patients who were evaluable, and only 2 ultimately rejected their marrow grafts, 1 with subsequent return of his own marrow function. Five patients without evidence in vitro of sensitization were transplanted after immunosuppression with cyclophosphamide alone; none of these rejected their grafts. These studies show that sensitized bone marrow transplant recipients can be successfully transplanted after optimal donor selection and multiagent immunosuppression.