BONE MARROW TRANSPLANTATION IN A LEUKEMIC PATIENT FOLLOWING IMMUNOSUPPRESSION WITH ANTITHYMOCYTE GLOBULIN AND TOTAL BODY IRRADIATION

Abstract

SUMMARY Previous studies in mice had demonstrated the importance of high radiation exposure rates in achieving immunosuppression for foreign bone marrow transplantation. Information gained from these and other laboratory studies utilizing antilymphocyte serum suggested an immunosuppressive protocol that would not require exposure of a patient to lethal total body irradiation yet permit transplantation of allogeneic bone marrow. A 50-year-old man with acute granulocytic leukemia was grafted with phenotypically HL-A-identical marrow after immunosuppression with horse antihuman thymocyte γ-globulin and total body irradiation exposure of 500 R given at a high rate. Engraftment was demonstrated by complete repopulation of the host by donor-type red cells. Hematological data and the absence of an aberrant cell line diagnostic for the leukemic cells following treatment suggested engraftment of platelets and granulocytes also. Immunoglobulin typing, however, suggested a lack of donor lymphocyte cell repopulation. Although the patient died 122 days post-transplant following infection with Pneumocystis carinii and acute renal failure, there was neither clinical nor autopsy evidence of a relapse of his leukemia and no evidence of graft failure. The ability to engraft morrow following what is perhaps a “midlethal” radiation dose for humans represents a significant step toward finding an immunosuppressive regimen that could be utilized safely for treating other hemopoietic dyscrasias.