Background: The case of a patient with chronic myelogenous leukemia who underwent transplantation with highly purified CD34+ peripheral blood stem cells from his two-antigen-mismatched mother is reported. No graft-versus-host disease has been observed so far and stable engraftment has been documented until day 100.
Methods: Weekly analysis of chimerism in different cellular subsets was performed using a quantitative polymerase chain reaction assay for nine short tandem repeat markers in leukocytes sorted by fluorescence-activated cell sorting.
Results: No donor CD4+ or CD8+ T cells have been detected up to 3 months after transplantation, whereas a rapid increase of donor CD56+ natural killer (NK) cells was observed in parallel with circulating donor CD34+ progenitors and myeloid cells.
Conclusions: Because the graft contained virtually no T and NK cells, we believe the rapid in vivo generation of NK cells supported stable engraftment across the HLA barrier. The differentiation of CD34+ progenitors into NK cells might be a distinct feature of megadose stem cell transplants.