Blood, Vol. 96 No. 2 (July 15), 2000:
pp. 763-767
Microchimerism in bone marrow-derived CD34+ cells of
patients after liver transplantation
Dirk Nierhoff,
Henrik Csaba Horvath,
Joannis Mytilineos,
Markus Golling,
Octavian Bud,
Ernst Klar,
Gerhard Opelz,
Maria Teresa Voso,
Anthony D. Ho,
Rainer Haas, and
Stefan Hohaus
From the Departments of Internal Medicine V and Surgery, Institute
of Transplantation Immunology, University of Heidelberg, Clinical
Cooperation Unit, German Cancer Research Center, Heidelberg, Germany.
Lymphoid and dendritic cells of donor origin can be detected in the
recipient several years after a solid organ transplantation. This
phenomenon is termed microchimerism and could play a role in the
induction of tolerance. The fate of other hematopoietic cells
transferred by liver transplantation, in particular of stem and
progenitor cells, is unknown. For this reason, we studied peripheral
blood and bone marrow samples of 12 patients who had received a liver
transplant from an HLA-DR mismatched donor. Eight patients were
long-term survivors between 2.8 and 10.1 years after allografting.
CD34+ cells from bone marrow were highly enriched with
the use of a 2-step method, and a nested polymerase chain reaction was
applied to detect donor cells on the basis of allelic differences of
the HLA-DRB1 gene. Rigorous controls with DRB1 specificities equal to
the donor and host were included. In 5 of 8 long-term liver recipients,
donor-specific CD34+ cells could be detected in bone
marrow. Microchimerism in the CD34+ cell fraction did not
correlate to the chimeric status in peripheral blood. In conclusion,
our results demonstrate a frequent microchimerism among bone
marrow-derived CD34+ cells after liver transplantation.
The functional role of this phenomenon still needs to be defined.
