Lack of correlation between nucleated bone marrow cell dose, marrow CFU‐GM dose or marrow CFU‐E dose and the rate of HLA‐identical sibling marrow engraftment

There was no correlation between the rate of marrow engraftment and the number of nucleated bone marrow cells infused into 50 HLA-identical sibling marrow graft recipients with haematological malignancy conditioned with cyclophosphamide and fractionated total body irradiation, and immunosuppressed with either cyclosporin (42 patients) or methotrexate (eight patients). Similarly, there was no correlation between the number of marrow CFU-GM or CFU-e infused into recipients immunosuppressed with cyclosporin. The data show that recipients of HLA-identical sibling marrow allografts conditioned with cyclophosphamide and total body irradiation require less than 3 X 10(8) nucleated bone marrow cells/kg recipient weight to ensure engraftment, and throw doubt on the relevance of measuring committed progenitor cells in the donor marrow to assess the likelihood of subsequent haemopoietic reconstitution after matched sibling transplantation.