A multicenter trial of myeloablative clofarabine and busulfan conditioning for relapsed or primary induction failure AML not in remission at the time of allogeneic hematopoietic stem cell transplantation.

Allogeneic hematopoietic cell transplantation (HCT) may produce long-term survival in AML after relapse or primary induction failure (PIF). However, outcomes of HCT performed for AML not in remission are historically poor given high relapse rates and transplant-related mortality. Preliminary studies suggest conditioning with clofarabine and myeloablative busulfan (CloBu4) may exert significant anti-leukemic effects without excessive toxicity in refractory hematologic malignancies. A prospective multicenter phase II trial was conducted to determine the efficacy of CloBu4 for patients proceeding directly to HCT with AML not in remission. Seventy-one patients (median age: 56 years) received CloBu4. At day 30 after HCT, 90% achieved morphologic remission. The incidence of non-relapse mortality and relapse at 2 years was 25% and 55%, respectively. The 2-year overall survival (OS) and event-free survival (EFS) were 26% and 20%, respectively. Patients entering HCT in PIF had significantly greater EFS than those in relapse (34% vs 8%; P<0.01). Multivariate analysis comparing CloBu4 with a contemporaneous cohort (Center for International Blood and Marrow Transplantation Research) of AML not in remission receiving other myeloablative conditioning (n=105) demonstrated similar OS (HR: 1.33, 95% confidence interval: 0.92-1.92; P=0.12). HCT with myeloablative CloBu4 is associated with high early response rates and may produce durable remissions in select patients with AML not in remission.

Clinical laboratory markers of inflammation as determinants of chronic graft-versus-host disease activity and NIH global severity.

Chronic graft-versus-host disease (cGVHD) remains a major cause of non-relapse morbidity and mortality after allogeneic hematopoietic stem cell transplantation. Currently there are no accepted measures of cGVHD activity to aid in clinical management and disease staging. We analyzed clinical markers of inflammation in the sera of patients with established cGVHD and correlated those with definitions of disease activity. In all, 189 adults with cGVHD (33% moderate and 66% severe according to National Institutes of Health (NIH) global scoring) were consecutively enrolled onto a cross-sectional prospective cGVHD natural history study. At the time of evaluation, 80% were receiving systemic immunosuppression and failed a median of four prior systemic therapies (PST) for their cGVHD. Lower albumin (P<0.0001), higher C-reactive protein (P = 0.043), higher platelets (P = 0.030) and higher number of PST (P<0.0001) were associated with active disease defined as clinician's intention to intensify or alter systemic therapy due to the lack of response. Higher platelet count (P = 0.021) and higher number of PST (P<0.0001) were associated with more severe diseased defined by NIH global score. This study identified common laboratory indicators of inflammation that can serve as markers of cGVHD activity and severity.

Red blood cell-incompatible allogeneic hematopoietic progenitor cell transplantation.

Transplantation of hematopoietic progenitor cells from red cell-incompatible donors occurs in 30-50% of patients. Immediate and delayed hemolytic transfusion reactions are expected complications of red cell-disparate transplantation and both ABO and other red cell systems such as Kidd and rhesus can be involved. The immunohematological consequences of red cell-incompatible transplantation include delayed red blood cell recovery, pure red cell aplasia and delayed hemolysis from viable lymphocytes carried in the graft ('passenger lymphocytes'). The risks of these reactions, which may be abrupt in onset and fatal, are ameliorated by graft processing and proper blood component support. Red blood cell antigens are expressed on endothelial and epithelial tissues in the body and could serve to increase the risk of GvHD. Mouse models indicate that blood cell antigens may function as minor histocompatibility antigens affecting engraftment. Similar observations have been found in early studies of human transplantation for transfused recipients, although current conditioning and immunosuppressive regimens appear to overcome this affect. No deleterious effects from the use of red cell-incompatible hematopoietic grafts on transplant outcomes, such as granulocyte and platelet engraftments, the incidences of acute or chronic GvHD, relapse risk or OS, have been consistently demonstrated. Most studies, however, include limited number of patients, varying diagnoses and differing treatment regimens, complicating the detection of an effect of ABO-incompatible transplantation. Classification of patients by ABO phenotype ignoring the allelic differences of these antigens also may obscure the effect of red cell-incompatible transplantation on transplant outcomes.

A randomized phase III clinical trial of autologous blood stem cell transplantation comparing cryopreservation using dimethylsulfoxide vs dimethylsulfoxide with hydroxyethylstarch.

Hematopoietic stem cells intended for autologous transplantation are usually cryopreserved in solutions containing 10% dimethylsulfoxide (DMSO, v/v) or 5% DMSO in combination with 6% hydroxyethylstarch (HES, w/v). We performed a single-blinded, randomized study comparing these cryoprotectant solutions for patients undergoing autologous peripheral blood stem cell (PBSC) transplantation. A total of 294 patients were evaluable; 148 received cells frozen with 10% DMSO and 146 received cells frozen in 5% DMSO/6% HES. Patients who received cells frozen with the combination cryoprotectant recovered their white blood cell count >or=1.0 x 10(9)/l at a median of 10 days, one day faster than those who received PBSC frozen with DMSO alone (P=0.04). Time to achieve neutrophil counts of >or=0.5 x 10(9) and >or=1.0 x 10(9)/l were similarly faster for the recipients of the cells frozen in the combination solution. This effect was more pronounced for patients who received quantities of CD34+ cells higher than the median for the population. Median time to discontinuation of antibiotic use was also one day faster for the recipients of cells cryopreserved with DMSO/HES (P=0.04). In contrast, median times to recovery of platelet count >or=20 x 10(9)/l were equivalent for each group (10 days; P=0.99) and the median numbers of red cell and platelet transfusions did not differ.

Treating refractory chronic graft-versus-host disease with extracorporeal photochemotherapy.

Extracorporeal photochemotherapy (ECP; photopheresis), an immunomodulatory therapy, has previously demonstrated promising results in treating chronic graft-versus-host disease (cGvHD). We treated six patients (ages 33-54 years) with long-standing refractory extensive-stage cGvHD. ECP was performed thrice weekly initially in all patients. Concomitant therapies included prednisone (n=6), tacrolimus (n=5), cyclosporin A (n=2), hydroxychloroquine (n=2), mycophenolate mofetil (n=1), and psoralen plus ultraviolet A radiation (n=1). After an average of 7.2 months (range, 2-13 months) of ECP, all patients experienced either improvement or stabilization in sclerodermatous skin changes, as well as partial improvements in liver enzyme levels. Skin softening occurred in four patients and was noted as early as 3-8 weeks into treatment. Two patients were able to taper steroid therapy, and two patients were able to taper ECP to twice weekly. ECP was well tolerated. Our results support those of previous studies, suggesting that ECP may be beneficial in patients with refractory cGvHD.

Long-term follow-up of intensive ara-C-based chemotherapy followed by bone marrow transplantation for adult acute lymphoblastic leukemia: impact of induction Ara-C dose and post-remission therapy.

We report single institution outcome of brief, intensive ara-C-based chemotherapy using bone marrow transplantation as primary intensification for untreated adult patients with acute lymphoblastic leukemia (ALL). Overall disease-free and overall survival were inferior to those reported with prolonged chemotherapy modeled on pediatric protocols. Survival and disease-free survival were superior for patients receiving allogeneic BMT compared with chemopurged autologous transplant or maintenance chemotherapy (patients ineligible for or declining BMT). In multivariate analysis, non-L2-FAB, higher ara-C dose, absence of CNS disease, non-Ph1+ karyotype, allogeneic BMT, T cell phenotype, and younger age were associated with improved disease-free survival. Autologous BMT was not superior to chemotherapy, and appears unlikely to provide adequate curative treatment for most adult ALL patients if not followed by maintenance.

Trafficking of CD34+ cells into the peripheral circulation during collection of peripheral blood stem cells by apheresis.

The number of CD34+ cells collected during apheresis is related to the volume of blood processed. In large-volume apheresis (LVL) procedure, more cells can be collected than were originally present in the peripheral blood at the start of the collection procedure. We prospectively studied the levels of CD34+ cells in the blood and apheresis product during LVL procedures for 21 patients with acute myelogenous leukemia or multiple myeloma. These patients experienced a slow decline in blood CD34+ cell concentrations during the apheresis procedure. No patient demonstrated a sustained rise in CD34+ cell counts as a result of the procedure. The number of CD34+ cells collected exceeded the number calculated to be in the peripheral blood at the start of the procedure by an average of 3.0-fold. The efficiency of collection for CD34+ cells averaged 92.6% and did not vary with speed of blood processing, diagnosis, or mobilization regimen. The calculated release of CD34+ cells from other reservoirs into the peripheral blood averaged 3.71 x 10(6)/min (range, 0.36-13.7 x 10(6)/min), and correlated (r = 0.82) with the concentration of these cells in the peripheral blood at the start of the procedure. These data show that the apheresis procedure used in this study does not affect the release of CD34+ cells in a cytokine-treated patient. LVL will result in collection of larger quantities of CD34+ cells than procedures involving processing of smaller volumes of blood, but the number of cells collected is limited by the rate of release of these cells into the peripheral circulation where they are accessible for collection.

Hematopoietic stem cell transplantation between red cell incompatible donor-recipient pairs.

Transplantation between red cell-disparate donor and recipient is feasible with minimal increase in the risk of transplantation if consideration is given to the immunohematological consequences of the transplant. The risks of immediate and delayed hemolysis must be managed. Some recipients will experience a delay in the recovery of red blood cells.

Experiences of donors enrolled in a randomized study of allogeneic bone marrow or peripheral blood stem cell transplantation.

The experiences of 69 (38 marrow and 31 peripheral blood stem cell [PBSC]) donors participating in a randomized trial comparing allogeneic bone marrow with PBSC transplantation were studied. Marrow was collected by means of standard harvest techniques and general or regional anesthesia. PBSC donors were treated with 5 to 7 days of filgrastim at a dose of 16 microg/kg/d and underwent 1 to 3 days of apheresis to obtain 5 x 10(6) CD34(+) cells per kilogram recipient weight. Donors completed questionnaires describing their health experiences before, during, and then weekly after donation until return to baseline status. Both marrow and PBSC donors reported minimal fluctuation in symptoms measuring emotional status. In contrast, both groups of donors reported deterioration in physical status starting with administration of filgrastim (PBSC donors) or after the marrow collection procedure. The symptom burden reported was similar, with pain a prominent symptom for both groups. Equivalent mean levels of maximal pain, average pain, and pain duration through the day were reported, although toxicity peaks occurred at different time points during the harvest procedures. All PBSC donors but only 79% of marrow donors reported good physical status by 14 days after the harvest procedures. These data demonstrate similar levels of physical discomfort for hematopoietic stem cell donors regardless of the collection procedure used, but a quicker resolution of symptoms for PBSC donors.

Platelet transfusion for patients with cancer: clinical practice guidelines of the American Society of Clinical Oncology.

OBJECTIVE: To determine the most effective, evidence-based approach to the use of platelet transfusions in patients with cancer. OUTCOMES: Outcomes of interest included prevention of morbidity and mortality from hemorrhage, effects on survival, quality of life, toxicity reduction, and cost-effectiveness. EVIDENCE: A complete MedLine search was performed of the past 20 years of the medical literature. Keywords included platelet transfusion, alloimmunization, hemorrhage, threshold and thrombocytopenia. The search was broadened by articles from the bibliographies of selected articles. VALUES: Levels of evidence and guideline grades were rated by a standard process. More weight was given to studies that tested a hypothesis directly related to one of the primary outcomes in a randomized design. BENEFITS/HARMS/COST: The possible consequences of different approaches to the use of platelet transfusion were considered in evaluating a preference for one or another technique producing similar outcomes. Cost alone was not a determining factor. RECOMMENDATIONS: Appendix A summarizes the recommendations concerning the choice of particular platelet preparations, the use of prophylactic platelet transfusions, indications for transfusion in selected clinical situations, and the diagnosis, prevention, and management of refractoriness to platelet transfusion. VALIDATION: Five outside reviewers, the ASCO Health Services Research Committee, and the ASCO Board reviewed this document. SPONSOR: American Society of Clinical Oncology

Transplantation of ABO-incompatible bone marrow and peripheral blood stem cell components.

Hemolysis may occur during infusion of an ABO-incompatible HSC component if the recipient has isoagglutinins directed against donor red blood cells, or later as a result of the production by donor lymphocytes of isoagglutinins directed against recipient ABO-antigens. Peripheral blood stem cell (PBSC) components collected by apheresis contain few red cells but considerably greater numbers of lymphocytes than marrow. We reviewed the transplant courses of 158 recipients of marrow (n = 90) or PBSC (n = 68) from HLA-identical, ABO-incompatible sibling donors. No patient experienced immediate or delayed hemolysis attributable to the ABO incompatibility. Recipients of minor ABO-incompatible red cell-replete marrow required fewer red cell transfusions during the first week after transplantation than recipients of PBSC or marrows depleted of red cells; the red cell transfusion requirements for the following 3 weeks did not differ. The maximum level of bilirubin did not differ for patients classified by ABO incompatibility or source of HSC. The development of positive antiglobulin tests occurred for eight marrow recipients from a separate group of 22 patients (17 marrow, five PBSC) for whom this testing was performed. None of these patients developed overt hemolysis. These data indicate that hemolysis complicating ABO-incompatible transplantation is not common after either marrow or PBSC transplantation. Bone Marrow Transplantation (2000) 26, 749-757.

Granulocyte colony-stimulating factor given to donors before apheresis does not prevent aplasia in patients treated with donor leukocyte infusion for recurrent chronic myeloid leukemia after bone marrow transplantation.

We conducted 2 sequential studies of donor leukocyte infusion (DLI) in 26 patients with chronic myeloid leukemia in hematologic relapse after unmodified allogeneic bone marrow transplantation. In the first study, cells for DLI were collected from 13 donors who were not treated with granulocyte colony-stimulating factor (G-CSF) (group 1). In the second study, cells were collected from 13 donors who received G-CSF before apheresis (group 2) in an attempt to avoid aplasia after DLI. Patients in group 2 received 550-fold more CD34+ cells than those in group 1. We found no significant difference in the incidence (31% versus 22%), onset time (41 vs. 48 days), or duration (15 vs. 14 days) of cytopenia after DLI in the 2 groups. G-CSF given to donors before collection of cells did not prevent aplasia. These findings support the hypothesis that the pathogenesis of aplasia after DLI is not restricted to the destruction of recipient hematopoietic cells but also involves failure of donor hematopoiesis by undefined mechanisms.

Enumeration of HPC in mobilized peripheral blood with the Sysmex SE9500 predicts final CD34+ cell yield in the apheresis collection.

Enumeration of CD34+ cells in the peripheral blood before apheresis predicts the quantity of those cells collected, although the cytometric techniques used are complex and expensive. We found that a subpopulation of lysis-resistant cells in the peripheral blood, identified by the Sysmex SE9500 and designated as HPC, can serve as a surrogate marker predictive of the yield of CD34+ cells. Spearman's rank statistics were used to examine the correlation between WBC, MNC, HPC and CD34+ cells in the peripheral blood and final CD34+ cell yield for 112 samples of peripheral blood and matching apheresis collections from 66 patients and donors. The results indicate that WBC and MNC in the peripheral blood were poor predictors of CD34 content, while HPC gave a correlation coefficient of 0.62. The positive predictive values of different cutoff levels of HPC in the peripheral blood ranging from 5 to 50 x 106/l increased from 0.80 to 0.93 when the target collection was 1 x 106cells/kg. However, for patients with HPC levels below various cutoff levels, the proportion of the collections not reaching that target goal ranged between 0.36 and 0.43, indicating that most collections will still exceed the target goal of CD34+ cells. When the target collection was 2.5 x 106 CD34+ cells/kg, the positive predictive value was lower and negative predictive value was higher.

Three to six year follow-up of normal donors who received recombinant human granulocyte colony-stimulating factor.

One hundred and one donors who had received filgrastim (rhG-CSF) for the purpose of donating either granulocytes or peripheral blood stem cells (PBSC) for their relatives more than 3 years ago were contacted. All donors had received daily rhG-CSF at a median dose of 16 microg/kg/day (range 3-16) for a median of 6 days (range 3-15 days). All collection procedures were completed and short-term side-effects of rhG-CSF were mild in the majority of the donors. At a median time interval of 43.13 months (range 35-73), the donors were contacted to assess whether adverse effects related to rhG-CSF administration had occurred. Prior to rhG-CSF two donors had cancer, one had a myocardial infarction, one was hepatitis C virus positive, one had a history of sinusitis, one had Graves' disease and two had arterial hypertension. None worsened with the rhG-CSF administration but the donor with a history of infarction had an episode of angina following apheresis, and the donor with Graves' disease had a stroke 15 months after rhG-CSF. Two pregnancies occurred after the rhG-CSF administration and one donor was 2-3 weeks pregnant during rhG-CSF treatment. Three pregnancies resulted in two normal births and one in a spontaneous abortion of a pregnancy which occurred more than 2 years following rhG-CSF. In the time following rhG-CSF administration two donors developed cancer (breast and prostate cancer) at a follow-up of 70 and 11 months, respectively. One donor developed lymphadenopathy 38 months after the rhG-CSF, which spontaneously resolved. Blood counts were obtained in 70 donors at a median follow up of 40.4 months (range 16.8-70.8). Hematocrit was 43% (median, range 36.8-48), white blood cells were 5.7 x 109/l (median, range 3-14), granulocytes 3.71 x 109/l (median, range 1. 47-10.36), lymphocytes 1.67 x 109/l (median, range 0.90-3.96), monocytes 0.46 x 109/l (median, range 0.07-0.87) and platelet counts were 193.0 x 109/l (median, range 175.0-240.0). This study indicates that short-term administration of rhG-CSF to normal donors for the purpose of mobilizing the PBSC or granulocytes appears safe and without any obvious adverse effects more than 3 years after the donation. Bone Marrow Transplantation (2000) 25, 85-89.

Collection of peripheral blood progenitor cells with an automated leukapheresis system.

BACKGROUND: Apheresis devices designed for the collection of mature blood elements are being used for the collection of peripheral blood progenitor cells (PBPCs). The collection of PBPCs differs from that of other cells in the rarity of the target cell and in the fact that donors may undergo several days of collection. A consequence of this process may be a depletion of blood cells such as platelets from the blood. The disposable set and operating software for an apheresis device (Spectra, COBE BCT) was modified by the manufacturer to automate the collection of PBPCs and reduce the collection of unwanted blood cells. STUDY DESIGN AND METHODS: A study was initiated to compare the collection of PBPCs with the new device, the AutoPBSC (version [V]6.0 with AutoPBSC tubing set), and that with the MNC (mononuclear cell) procedure (V4.7 with white cell tubing set), for patients and healthy donors. RESULTS: Patients whose blood was processed by either theV6.0 orV4.7 procedure achieved the target dose of 5 x 10(6) CD34+ cells per kg of patient weight in similar numbers of procedures, even though the calculated collection efficiency for CD34+ cells using the automated V6.0 procedure was significantly less than that with the V4.7 procedure for both allogeneic donors and patients donating PBPCs. The collection efficiency for platelets was lower with the V6.0 procedure, and components collected in this manner contained fewer platelets. Apheresis by the V6.0 procedure required 30 to 60 more minutes per procedure than apheresis by the V4.7 procedure. Review of engraftment kinetics after transplantation did not reveal any effect of the collection procedure on recipients of either allogeneic or autologous transplants. CONCLUSION: The collection efficiencies of the V6.0 procedure for both CD34+ cells and mature blood cells are lower than those of the V4.7 procedure. The lower collection efficiency for platelets results in a smaller drop in peripheral blood platelet count after the procedure. The automated features of the V6.0 procedure may simplify PBPC collection, but this procedure requires a longer apheresis.

A phase I-II clinical trial to evaluate removal of CD4 cells and partial depletion of CD8 cells from donor marrow for HLA-mismatched unrelated recipients.

We conducted a phase I-II clinical trial to test the hypothesis that removal of CD4 cells from an HLA-mismatched unrelated marrow graft would substantially reduce the risk of grades III-IV graft-versus-host disease (GVHD) and that retention of a specified number of CD8 cells in the graft would be sufficient to prevent rejection. Patients were eligible for this study when an HLA-A, -B, or -DRB1-matched unrelated donor could not be identified. HLA matching of the donor and recipient was based on typing of HLA-A and -B antigens by serologic methods and by typing of HLA-DRB1 alleles by molecular methods, and donors were selected when disparity was limited to a single HLA-DRB1 allele or a single HLA-A or -B antigen. Twenty-seven patients with hematologic malignancy or aplastic anemia were prepared to receive a transplant with conventional regimens of cyclophosphamide and fractionated total body irradiation, and a standard regimen of methotrexate and cyclosporine was given for GVHD prophylaxis. CD4 cells were removed from the donor marrow, and the numbers of CD8 cells were adjusted systematically in graded steps for successive patients, depending on the occurrence of grades III-IV GVHD or graft failure in previously enrolled patients. Removal of CD4 cells did not cause graft rejection or appreciably decrease the risk of grades III-IV GVHD. Depletion of CD8 cells was associated with an increased risk of rejection with either HLA-DRB1 disparity or with HLA-A or -B disparity. With either type of disparity, the risk of grades III-IV GVHD is likely to be higher than 15% at any dose of CD8 cells associated with less than 5% risk of graft failure. The absence of graft failure associated with CD4 depletion supports the hypothesis that donor CD4 cells are not essential for preventing marrow graft rejection in humans. The correlation between graft failure and the number of CD8 cells in the donor marrow supports the hypothesis that donor CD8 cells help to prevent marrow graft rejection.

The predictive value of white cell or CD34+ cell count in the peripheral blood for timing apheresis and maximizing yield.

BACKGROUND: The collection of peripheral blood stem and progenitor cells (PBPCs) for transplantation can be time-consuming and expensive. Thus, the utility of counting CD34+ cells and white cells (WBCs) in the peripheral blood was evaluated as a predictor of CD34+ cell yield in the apheresis component. STUDY DESIGN AND METHODS: The WBC and CD34+ cell counts in the peripheral blood and the apheresis components from 216 collections were assessed. Sixty-three patients underwent mobilization with chemotherapy plus filgrastim, and 17 patients and 14 allogeneic PBPC donors did so with filgrastim alone. The relationship between the number of WBC and CD34+ cells in the peripheral blood and in the apheresis component was analyzed by using rank correlation and linear regression analysis. RESULTS: The correlation coefficient for CD34+ cells per liter of peripheral blood with CD34+ cell yield (x 10(6)/kg) was 0.87 (n = 216 collections). This correlation existed for many patient and collection variables. However, patients with acute myeloid leukemia had fewer CD34+ cells in the apheresis component at any level of peripheral blood CD34+ cell count. Components collected from patients with CD34+ cell counts below 10 x 10(6) per L in the peripheral blood contained a median of 0.75 x 10(6) CD34+ cells per kg. When the WBC count in the blood was below 5.0 x 10(9) per L, the median number of CD34+ cells in the peripheral blood was 5.6 x 10(6) per L (range, 1.0-15.5 x 10(6)/L). A very poor correlation was found between the WBC count in the blood and the CD34+ cell yield (p = 0.12, n = 158 collections). CONCLUSION: The number of CD34+ cells, but not WBCs, in the peripheral blood can be used as a predictor for timing of apheresis and estimating PBPC yield. This is a robust relationship not affected by a variety of patient and collection factors except the diagnosis of acute myeloid leukemia. Patients who undergo mobilization with chemotherapy and filgrastim also should undergo monitoring of peripheral blood CD34+ cell counts, beginning when the WBC count in the blood exceeds 1.0 to 5.0 x 10(9) per L.

Post-thaw removal of DMSO does not completely abrogate infusional toxicity or the need for pre-infusion histamine blockade.

BACKGROUND: The infusion of PBSC or BM cells cryopreserved with DMSO is associated with frequent, but generally minor, toxicity. The incidence and severity of infusion-related toxicity is proportional to the amount of DMSO infused. In an attempt to reduce the incidence of symptoms reported by patients receiving cryopreserved PBSC and to avoid the necessity of diphenhydramine premedication, we studied the infusion of PBSC components from which the DMSO was depleted after thawing. METHODS: This was a Phase I/II study of post-thaw removal of DMSO. Patients undergoing autologous PBSC transplantation with components cryopreserved using 10% DMSO were eligible. The PBSC components were thawed, diluted with 10% dextran-40 and 5% HSA, centrifuged to remove the DMSO, resuspended in dextran and HSA, and infused without prior medication of the patient. Visual analog scale questionnaires were used for measurement of infusion-related symptoms. RESULTS: Five patients were enrolled on this study and received washed PBSC components. One patient experienced severe infusion-related toxicity and the study was stopped for safety reasons. Events experienced by these patients included flushing (two patients), emesis (three patients), and post-infusion rigors (two patients). Two patients reported an increase in nausea after the infusion. All patients achieved granulocyte engraftment (an ANC > 0.5 x 10(9)/L) at a median of 14 days and platelet engraftment (platelet count without transfusion > 20 x 10(9)/L) at a median of 11 days. No patient required infusion of additional cells because of engraftment failure. DISCUSSION: In theory, the post-thaw reduction of DMSO should reduce the risk of infusion-related toxicity that is commonly attributed to DMSO. Although not demonstrated by the data developed from this study, effective reduction in DMSO could also eliminate the need for pre-infusion histamine blockade. However, the technique used in this study was not adequate and a more rigorous depletion technique must be developed to completely abrogate clinical infusion-related toxicity.

Isolation of CD34+ cells from blood stem cell components using the Baxter Isolex system.

The CD34 antigen is expressed by human hematopoietic progenitor and stem cells. These cells are capable of reconstituting marrow function after marrow-ablative chemo-radiotherapy. Several different technologies have been developed for the separation of CD34+ cells from bone marrow or peripheral blood stem cell (PBSC) components. We used an immunomagnetic separation technique to enrich CD34+ cells from PBSC components in anticipation of autologous transplantation for patients with B lymphoid malignancies. Twenty-nine patients enrolled on this study and received mobilization chemotherapy followed by G-CSF. Of these, 21 achieved a peripheral blood CD34+ cell level of at least 2.0 x 10(4)/l required by protocol for separation of the stem cell components. A median of three components per patient was collected for processing. The average CD34+ cell concentration in the components after apheresis was 1.0 +/- 1.2%. After the CD34+ cell selection, the enriched components contained 0.6 +/- 0.6% of the starting nucleated cells. The recovery of CD34+ cells, however, averaged 58.4 +/- 19.2% of the starting cell number, with a purity of 90.8 +/- 6.5%. Overall depletion of CD34- cells was 99.96 +/- 0.06%. Nineteen patients were treated with marrow-ablative conditioning regimens and received an average of 6.2 +/- 2.0 x 10(6) CD34+ cells/kg body weight. These patients recovered to an ANC >0.5 x 10(9)/l at a median of 11 days (range 8-14), and platelet transfusion independence at a median of 9 days (range 5-13). Four patients died of transplant-related complications or relapse before 100 days after transplantation. No patient required infusion of unseparated cells because of failure of sustained bone marrow function. These data demonstrate that peripheral blood-derived CD34+ cells enriched by use of an immunomagnetic separation technique are capable of rapid engraftment after autologous transplantation.