Clonogenic assays and engraftment in allogeneic bone marrow transplantation

The significance of clonogenic assays for determining the hematopoietic potential of bone marrow grafts is still a matter of controversy. We determined the number of myeloid (GM-CFU), early erythroid (BFUe) and mixed (CFU-GEM) clones in 23 consecutive allogeneic bone marrow grafts. The growth of GM-CFU was stimulated by placental-conditioned medium, whereas both phytohemagglutinin-stimulated leucocyte-conditioned medium (PHA-LCM) and 'pluripoietin' from the 5637 cell line served as equally efficient stimulators of BFUe and CFU-GEM growth. Plating efficiency (e.o.p.) of GM-CFU and numbers of myeloid and mixed progenitors transplanted per kg body weight were significantly lower in those patients who died in the aplastic phase 2-6 weeks postgrafting (n = 4). These data show that low numbers of clonogenic cells, in particular GM-CFU, indicate a higher risk of death from infection following bone marrow transplantation (BMT) and argue for a contribution of GM-CFU in the seeding of an aplastic bone marrow.