Summary:ment, stem cell transplantation is increasingly being used in younger patients with poor prognosis CLL. [2][3][4][5] Autologous stem cell transplantation in patients with CLL has been Autologous PBPC transplantation is a potentially curative treatment for patients with chronic lymphocytic hampered by two major obstacles. First, most patients are older, which makes myeloablative radiochemotherapy with leukemia (CLL). As the autografts are frequently contaminated with large numbers of tumor cells, we have prolonged cytopenias, as usually seen after autologous bone marrow transplantation (BMT), particularly difficult. Using studied double purging of PBPC using immunomagnetic CD34 ؉ cell selection (Isolex 300i) followed by negative peripheral blood progenitor cells (PBPC) instead of BM promises to reduce this complication. 6 Second, stem cell depletion with anti-CD19/20/23/37-labeled immunomagnetic beads. In four small-scale experiments using PBPC grafts from patients with CLL are frequently contaminated with large amounts of leukemic cells, which raises the from patients with CLL or leukemic low-grade lymphoma, double purging resulted in CD34 ؉ enrichment question of ex vivo purging of the graft. Although a clear-cut benefit of purging has not been from 0.9-4.4% to 95. 8-99.4%. Lymphoma cells were always undetectable by FACS and PCR (CDR3 orshown for any disease to date, recent data indicate that relapse after autologous stem cell transplantation may arise t(14;18)) after negative depletion. Next, seven heavily contaminated full grafts from five patients with CLL or from tumor cells reinfused with the graft. 7-9 Because of the usually heavy leukemic contamination of blood and BM in lymphoplasmocytoid immunocytoma were subjected to the double purging procedure, resulting in a CD34 ؉ CLL, the use of unpurged grafts appears to be associated with considerable risks in patients with this disease. Moreenrichment from 1.6% (0.7-5.6) to 98.5% (96-99.8). The CD34 ؉ yield after double purging was 1.3-over, the Dana-Farber group 4 reported that relapses after ABMT for CLL occurred exclusively in patients whose 6.3 ؋ 10 6 /kg, according to a median recovery of 32%. The overall reduction of lymphoma cells was 5.6 (Ͼ4.6-autografts showed molecular evidence of tumor cell contamination after purging. Thus, purging has been performed 6) log. Although CLL cells were completely absent after purging in five cases as assessed by FACS, all grafts in the vast majority of autotransplants performed in patients with CLL to date. remained PCR positive. The first two patients have been reinfused with double selected products after myeloablAt present, immunomagnetic selection of CD34 + cells appears to be one of the most efficient methods of depletion ative radiochemotherapy and showed prompt and uneventful hematopoietic engraftment. We conclude of unwanted cells from PBPC grafts, resulting in a reduction of B cells of approximately 3 log. 10 Probably due that without significant loss of CD34 ؉ cells, negative depletion adds 2 log of ...

Autologous peripheral blood progenitor cell (PBPC) transplantation is increasingly being used for treatment of indolent lymphomas. Since involvement of bone marrow and peripheral blood is frequent and methods to reduce the lymphoma cell load of PBPC grafts are thus highly desirable, we have studied purging of PBPC comparing two immunomagnetic