BONE-MARROW TRANSPLANTATION FOR LEUKEMIA AFTER CONDITIONING WITH BUSULFAN AND CYCLOPHOSPHAMIDE - BONE-MARROW MORPHOLOGY IN THE EARLY RECOVERY PHASE

The bone marrow morphology of fifty patients with leukemia was analyzed before and two weeks after allogeneic bone marrow transplantation and compared to that of ten normal, healthy control subjects. Conditioning of the marrow graft recipients had been carried out with a combination of 16 mg / kg of Busulfan and 120 mg / kg of cyclophosphamide. The bone marrow at two weeks after transplant showed characteristic features that were unique for this clinical setting. Regenerative precursor cells with a distinct morphology commonly formed clusters or islands. Although mixed, multilinear islands were seen; the majority of islands were unilinear with a homogeneous cell content. These hematopoietic colonies were in direct proximity to degenerated cells of presumed host origin. No damage to the microenvironment was seen, the most characteristic finding being large, uniform, unilocular fat cells in close proximity to regenerative precursor cells. These morphologic changes are indicative of a complete and persistent marrow engraftment.