The mechanism of recurrence of mouse myeloid leukaemia after total body irradiation and bone marrow transplantation.

Abstract

RFM mice were X-irradiated (9.5 Gy) 3, 4, 5, 6 or 7 days after inoculation of a transplantable strain-specific myeloid leukaemia (ML) and were reconstituted or not with syngeneic or allogeneic bone marrow cells. Recurrent leukaemia was observed in mice with either type of the bone marrow transplant, indicating that ML cells survived the dose of 9.5 Gy of X-rays. ML cells exposed in vitro to high doses of X-rays (20, 30, 40, 50, 60 Gy) and injected into lethally irradiated syngeneic recipients were still capable of forming leukaemic colonies on the spleens. Higher doses (70, 80, 90 and 100 Gy) abolished the colony formation completely. Irradiated ML cells were also capable of causing leukaemia (hepatosplenomegaly) if inoculated into lethally irradiated CBA mice reconstituted with bone marrow cells of CBA or RFM mice. That was attributed to the release of a leukaemogenic factor from the ML cells, capable of transforming transplanted normal cells.