Stable engraftment after megadose blood stem cell transplantation across the HLA barrier: the case for natural killer cells as graft-facilitating cells.
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.
Bornhäuser
M
M
University Hospital Carl Gustav Carus, Dresden, Germany.
Thiede
C
C
Brendel
C
C
Geissler
G
G
Oelschlägel
U
U
Neubauer
A
A
Ehninger
G
G
D000328:Adult; D018952:Antigens, CD34 / Q000097:blood / Q000235:genetics; D002908:Chronic Disease; D006085:Graft Survival / Q000235:genetics / Q000502:physiology; D006680:HLA Antigens / Q000097:blood*; D006238:Haploidy; D018380:Hematopoietic Stem Cell Transplantation; D006801:Humans; D007694:Killer Cells, Natural / Q000502:physiology; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000628:therapy*; D008297:Male; D013601:T-Lymphocytes / Q000276:immunology
D018952:Antigens, CD34; D006680:HLA Antigens