Immunological conditioning of bone marrow for autotransplantation in childhood acute lymphoblastic leukaemia.

Samples of bone marrow from 32 leukaemic children were removed during remission and stored in liquid nitrogen for retransplantation during relapse. Subsequently two children in advanced stages of common acute lymphoblastic leukaemia (cALL) were transplanted with their own cryopreserved marrow cells, after intensive combination chemotherapy and high doses of radiation therapy. Before grafting, the marrow cells were treated with purified heterologous antibodies prepared against cALL antigens, to remove any residual tumour cells. The antibodies showed high cytotoxic activity against leukaemic cells of cALL type without interfering with normal haemopoietic stem cells. Evidence of take was obtained in one patient, who died on day 7 with cardiac failure. In the other patient the dose of nucleated marrow cells grafted was 1.9 x 10(8)/kg (86 000 CFU-C/kg). The patient achieved complete haematological recovery on day 27 and a normal platelet count after day 50 and is now in complete remission. Marrow cells collected during remission and treated with antileukaemic antibodies can repopulate bone marrow after conditioning of the recipient with high doses of radiation.