2ND TRANSPLANTATION USING ALLOGENEIC PERIPHERAL-BLOOD STEM-CELLS IN ABETA-THALASSEMIA MAJOR PATIENT FEATURING STABLE MIXED CHIMERISM

Allogeneic bone marrow transplantation (BMT) for beta-thalassaemia maj or carries the risks of disease recurrence due to residual thalassaemi c stem cells or true immune-mediated rejection. We report a thalassaem ic patient who displayed stable mixed chimaerism with only 5% donor-de rived cells for about 5 years after BMT. Displacement of host cells wa s accomplished by ambulatory non-myeloablative conditioning and alloge neic G-CSF mobilized peripheral blood stem cell transplantation from t he same donor, resulting in full reconstitution. Patients featuring st able mixed chimaerism after BMT may benefit from allogeneic cell thera py with immunocompetent lymphocytes and stem cells, whilst avoiding su pralethal conditioning.