Donor variables correlated with CD34+ cell yield only weakly, so no particular clinical characteristic can be used to exclude an individual as a PBPC donor if he or she is otherwise suitable for the apheresis procedure.

Summary. We report 13 normal peripheral blood stem cell (PBSC) donors who had a second PBSC collection for allogeneic transplantation performed after the first. The median interval between the first and second collection was 5 months. Mobilization was achieved with filgrastim (12 mg/ kg/d). No significant difference was found in the median pre-apheresis leucocyte count (×10 9 /l) between the two donations (40 . 2 v 38 . 5; P ¼ 0 : 91). The median apheresis yield (×10 6 CD34 þ cells/litre blood processed, first apheresis) was also similar (28 v 27 . 3; P ¼ 0 : 91). Filgrastim-related adverse events were comparable. These data suggest that second PBSC collections are feasible, similarly tolerated and provide comparable apheresis yields.Keywords: peripheral blood stem cell(s), filgrastim, normal donors, allogeneic blood stem cell transplantation.G-CSF-mobilized peripheral blood stem cells (PBSCs) are increasingly viewed as a promising alternative to marrow for allografting in patients with haematological malignancies (Goldman, 1995;Russell et al, 1996;Lane, 1996). The avoidance of general anaesthesia or invasive procedures, as well as blood transfusions (Anderlini et al, 1996c;Russell et al, 1996;Dreger et al, 1994), makes this approach particularly attractive for repeated PBSC collections, which may be required to treat post-transplant relapse or graft failure. It is unclear whether second PBSC collections (particularly if performed soon after the first) are associated with similar apheresis yields or whether G-CSF exposure impacts the subsequent PBSC mobilization efficiency. Available literature on allogeneic PBSC transplantation (Goldman, 1995;Russell et al, 1996;Lane, 1996) has not addressed this issue. At our institution we have had now the opportunity to perform a sizeable number of second PBSC collections. We therefore reviewed our donor database to report our experience. DONORS AND METHODS Normal apheresis donors.We retrospectively reviewed our PBSC donor database during a 18-month period ( January 1995/June 1996. During this time a total of 181 donors underwent PBSC collections after filgrastim mobilization for allografting in HLA-compatible related patients with haematological malignancies. 16 of them (9%) donated a second time at least 4 weeks after the first. In two of them the exact number of CD34 þ cells in the apheresis product could not be determined because of complex manipulations performed immediately after collection, and the apheresis charts of one donor were not available for review. These donors were considered inevaluable. The others (n ¼ 13) were included in the study. The protocol for PBSC collection was approved by the Institutional Review Board and written informed consent was obtained from each donor.Mobilization and apheresis. PBSC donors received daily filgrastim (6 mg/kg subcutaneously every 12 h) followed by daily continuous-flow leukapheresis through a bilateral peripheral venous access generally beginning on day 4 or day 5 of filgrastim administration. The amount of blood to be p...

Summary. We report 14 normal peripheral blood stem cell (PBSC) donors у 60 years of age who had cytokine mobilization followed by PBSC apheresis for allogeneic transplantation. Mobilization was achieved with filgrastim (6 mg/kg twice daily). Their median age was 63·5 years (range 60-77), and 43% had a positive medical history, mainly hypertension and/or cardiac problems. Their median pre-apheresis leucocyte count (× 10 9

Seventy-seven normal donors underwent leukapheresis for peripheral blood progenitor cell collection beginning on day 4 (n = 45) or day 5 (n = 32) of filgrastim mobilization (12 micrograms/kg/d). The two groups were comparable for age, weight, blood volumes processed during leukapheresis and target CD34+ cell dose to be collected. The day 5 schedule allowed a more consistent achievement of the target cell dose with one apheresis (P = 0.005) and resulted in the initial collection of a significantly larger number of CD34+ cells (P = 0.009). There was no statistically significant difference in the leukapheresis yield of lymphoid subsets and natural killer cells.

This phase I/II dose-escalation study examined the safety and efficacy of recombinant human thrombopoietin (rhTPO) and granulocyte colony-stimulating factor (G-CSF) for postchemotherapy mobilization of peripheral blood progenitor cells (PBPCs) in patients with advanced breast cancer. Patients received cyclophosphamide, etoposide, and cisplatin (CVP) followed by G-CSF (6 microg/kg twice a day) and rhTPO (0.6, 1.2, 2.4, or 3.6 microg/kg as a single dose on day 5 or as 3 doses on days 5, 7, and 9 after chemotherapy). PBPCs were collected by daily leukapheresis when the postnadir white blood cell count reached > or = 2 x 10(9)/L; leukapheresis was continued until acquisition of a target dose of > or = 5 x 10(6) CD34+ cells/kg. Mobilized PBPCs were transplanted into patients after additional high-dose chemotherapy with cyclophosphamide, carmustine, and thiotepa (CBT). Comparisons were made with contemporaneously treated, nonrandomized, control patients who received the same chemotherapy regimens and G-CSF support but who did not receive rhTPO. Of 32 evaluable patients receiving rhTPO and G-CSF after CVP, 91% required only 1 leukapheresis to achieve a target PBPC graft; by contrast, only 69% of 36 of the control patients achieved the target graft with just 1 leukapheresis (P = .026). A median of 26.7 x 10(6) CD34 cells/kg per leukapheresis was obtained from the rhTPO-treated patients compared with 11.5 x 10(6) cells/kg per leukapheresis from the controls (P = .09). Higher rhTPO doses appeared to yield more CD34+ cells. When PBPCs were infused after high-dose CBT chemotherapy, the median times to return of an absolute neutrophil count of 0.5 x 10(9)/L and a platelet count of 20 x 10(9)/L were 15 and 16 days, respectively; these values did not differ from those in the control group (15 days for both neutrophil and platelets). No patient developed anti-TPO antibodies. These results indicate that rhTPO safely and effectively augments the number of PBPCs mobilized with chemotherapy and G-CSF and can reduce the required number of leukaphereses. Further studies are also warranted in patients who are likely to experience suboptimal PBPC mobilization when treated with currently available techniques.