(P < 0AE01) compared with the BM group. The numbers of proven bacterial and viral infections were equally distributed between the three groups. In conclusion, recipients of allogeneic highly purified CD34 + PBSC or unmanipulated BM have higher lymphocyte subset counts at 6 months after transplantation than recipients of autologous CD34-selected PBSC. Infection rates and outcome, however, were not significantly different.Keywords: immune reconstitution, transplantation, purified blood stem cells, bone marrow, children. Lang et al, 2004). T-cell depletion of the graft, however, is known to impair T-cell reconstitution in the recipient, causing post-engraftment immunodeficiency and increased non-relapse mortality (Ochs et al, 1995;Davison et al, 2000).The aim of the present prospective study was to analyse and compare laboratory data of immunity in children receiving unmanipulated allogeneic BM or CD34-selected autologous or allogeneic PBSC. Patients and methods Patient characteristicsOver a 7-year period, 61 children were enrolled in this study after informed consent was obtained from parents. Eighteen patients died early after HSCT and could not be evaluated. Seven patients were lost to follow-up. Patients receiving autologous unselected PBSC (n ¼ 2), autologous PBSC + autologous BM (n ¼ 1) and unmanipulated UCB (n ¼ 2) were excluded. The remaining 31 patients (female: n ¼ 9, male: n ¼ 22) were diagnosed with severe aplastic anaemia . These patients underwent a total of 31 single HSCT and were studied with respect to immunological reconstitution. All 31 transplantations were grouped according to the different stem cell source used: autologous CD34-selected PBSC (group 1; n ¼ 10), allogeneic CD34-selected PBSC (group 2; n ¼ 12), and allogeneic unmanipulated BM (group 3; n ¼ 9) for statistical analysis. Transplantation characteristicsTransplantation characteristics are depicted in Table I. As conditioning regimen patients received busulfan-based (n ¼ 13), total body irradiation (TBI)-based (n ¼ 4) or other high dose chemotherapy-based regimens (n ¼ 13). In one patient, a reduced intensity immunoablative conditioning regimen was used. Graft manipulationAutologous PBSC were mobilised and harvested according to treatment protocols used. Allogeneic PBSC were mobilised by subcutaneous injection of granulocyte colony-stimulating factor (G-CSF, 5-10 lg/kg body weight/d) once daily for 5 consecutive days. Allogeneic and autologous PBSC were CD34-selected using the CD34 + Progenitor Cell Isolation Kit (Miltenyi Biotec, Bergisch Gladbach, Germany) applying a magnetic cell separation (MACS) technique using the Clini-MACS sorting device (Miltenyi Biotec) according to the manufacturer's instructions. The purity and recovery of the isolated CD34 + cells and the contamination with T-lymphocytes were assessed by flow cytometry. Autologous PBSC were frozen after dilution with a dimethylsulfoxide (DMSO) containing freezing solution using a computerised nitrogen freezer and stored at )193°C in the liquid phase of nitrogen until tran...

Diagnosis of acquired AATP which finally progressed to SAA was established in an eight-yr-old boy. PBSCT from an HLA-identical unrelated donor using high numbers of CD34+ selected stem cells was performed and resulted in complete remission for almost two yr. However, SAA reoccurred with 100% donor hematopoiesis and was reversed by a second CD 34+ selected PBSCT from the same donor. Declining blood cell counts after an interval of two yr indicated second relapse. Chimerism analysis in PB and BM aspirates revealed a small autologous cell population of 4-12% and 2-11%, respectively. Finally, a third transplantation with unmanipulated BM from the same donor resulted in sustained remission with 100% donor hematopoiesis. The patient is in complete remission for more than five yr following the third SCT. Late graft failure or late graft rejection known to occur after transplantation of highly purified CD34+ cells, or even graft exhaustion caused by stromal dysfunction due to the underlying disease necessitated a third transplantation. Regardless of the cause of relapse, transplantation of unmanipulated BM instead of highly purified PBSCTs led to a permanent and stable engraftment in a third attempt after two previous PBSCTs.