CD34+ cell dose and hematologic recovery in allogeneic peripheral blood stem cell transplantation

Allogeneic peripheral blood stem cell transplantation (Allo-PBSCT) has been performed as an alternative to bone marrow transplantation (BMT). Here we report poor mobilization with granulocyte-colony stimulating factor (G-CSF) and engraftment kinetics in Allo-PBSCT. Sixteen patients (aged 6-61 yr, median 34 yr) received allogeneic peripheral blood stem cells from related donors (aged 15-68 yr, median 37 yr) after myeloablative therapy. Nine of the patients had standard-risk disease and 7 had high-risk disease. The donors received G-CSF at a dose of 10 micrograms/kg/day by subcutaneous injection for 4 to 6 days. Peripheral blood stem cells were subsequently collected in 1 to 3 aphereses and infused immediately. All patients received G-CSF after transplantation. Fifteen patients underwent Allo-PBSCT and one underwent Allo-PBSCT plus BMT. The mean number of CD34+ cells infused in the 15 Allo-PBSCT patients was 6.32 x 10(6)/kg (range 1.28-14.20). The outcomes were compared with 9 identically treated patients who underwent Allo-BMT. The median times until engraftment for neutrophils > 500/microliter and platelets > 20,000/microliter were 14 (range 10-17) and 15 (range 11-50) days in the Allo-PBSCT group and 17 (range 13-29) and 20 (range 16-160) days in the Allo-BMT group, respectively (p = 0.0177 and p = 0.003). Three donors were considered to have poor mobilization (< 2 x 10(6) CD34+ cells/kg of the recipient); two of them yielded 1.28 and 1.78 x 10(6) CD34+ cells/kg in 3 apheresis procedures. The patients who received cells from these donors showed prompt neutrophil engraftment, but one showed delayed platelet engraftment and another died of grade IV acute GVHD before reaching 20,000 platelets/microliter. An additional bone marrow harvest was necessary from one donor because of poor mobilization(0.17 x 10(6) CD34+ cells/kg). Thus, Allo-PBSCT results in more rapid engraftment. It will be necessary to clarify the minimum CD34+ cell dose for complete engraftment in a larger series of trials.     

Transplantation of umbilical cord blood after myeloablative therapy: analysis of engraftment.

The possibility that umbilical cord and placental blood from an HLA-identical sibling might produce stable donor-derived lymphohematopoietic engraftment was tested in a patient with juvenile chronic myelogenous leukemia (JCML). After conditioning with high-dose busulfan and cyclophosphamide, cryopreserved umbilical cord blood, containing 0.5 x 10(8) nucleated cells/kg and 2.7 x 10(4) colony forming units-granulocyte, macrophage (CFU-GM)/kg, was infused. A leukocyte count greater than 1,000/microL, absolute neutrophil count (ANC) greater than 500/microL, and platelet count greater than 20,000/microL (untransfused) were observed on days 39, 39, and 47 after transplantation, respectively. Donor cell engraftment was documented in the peripheral blood and bone marrow by cytogenetic analysis, restriction fragment length polymorphism (RFLP), and polymerase chain reaction (PCR) as early as day 21. Furthermore, the donor origin of each lymphohematopoietic lineage (ie, CD5+ T cells, CD19/20+ B cells, CFU-GM, and burst-forming unit-erythrocyte [BFU-E]) was confirmed. On day 200, assays of the peripheral blood and bone marrow showed an abnormal proliferation of CFU-GM at low seeding densities in the absence of exogenous growth factors, as well as a hypersensitivity to granulocyte-macrophage colony-stimulating factor (GM-CSF), both pathophysiologic characteristics of JCML. Recurrent disease was confirmed histologically on day 225. Together, these results demonstrate that umbilical cord blood contains sufficient numbers of hematopoietic stem cells necessary for the engraftment of leukemia patients treated with myeloablative therapy and that the detection of "spontaneous" CFU-GM and hypersensitivity to GM-CSF after treatment is a marker of residual or recurrent disease in patients with JCML.     

Allogeneic peripheral blood stem cell transplantation in an elderly patient with myelodysplatic syndrome with myelofibrosis

Allogeneic peripheral blood stem cell transplantation (Allo-PBSCT) has in recent years become an alternative to allogeneic bone marrow transplantation because it facilitates rapid hematopoietic reconstitution without an increase in the incidence of severe graft-versus-host disease (GVHD). We report on a 61-year-old man with myelodysplastic syndrome (MDS) and myelofibrosis who received an allo-PBSCT from his HLA-matched 68-year-old brother. The preparative regimen consisted of busulfan and cyclophosphamide. Cyclosporin A and methotrexate were administered for GVHD prophylaxis. The donor was treated with granulocyte colony-stimulating factor (G-CSF) at a dose of 10 micrograms/kg/day subcutaneously for 4 consecutive days. A preparation of 4.04 x 10(6) CD34+ cells/kg recipient weight was collected in a single apheresis and infused immediately. Engraftment times to a neutrophil count greater than 500/microliter and platelet count greater than 2.0 x 10(4)/microliter were 15 days each. Acute GVHD of grade II developed, but was resolved with methylprednisolone. However, the patient died of thrombotic microangiopathy 97 days after his allo-PBSCT. Administration of G-CSF and apheresis in the donor were feasible and well tolerated. Allo-PBSCT may result in earlier engraftment and be especially beneficial to elderly patients with MDS.     

Complete remission of idiopathic myelofibrosis following donor lymphocyte infusion after failure of allogeneic transplantation: demonstration of a graft-versus-myelofibrosis effect

A patient with idiopathic myelofibrosis (IM) in the osteosclerotic phase received an allogeneic stem cell transplant. Hemopoietic engraftment was rapid, and full donor chimerism was observed on day +70. However, a few months later, replacement of donor hemopoiesis by the patient's 20q- cell clone was observed, followed by reappearance of the blood IM features, marrow fibrosis and osteosclerosis. At 8 months from transplant donor lymphocytes were infused, which induced chronic GVHD. This resulted in normalization of the blood, with disappearance of the fibrosis and osteosclerosis, effects which persisted 20 months later. This case provides evidence for a graft-versus-disease effect in IM.     

Mobilization and collection of peripheral blood CD34+ cells from patients with Fanconi anemia.

A potential therapeutic option for patients with Fanconi anemia is collection of peripheral blood stem cells prior to the development of severe pancytopenia. These hematopoietic cells potentially could be infused when symptomatic bone marrow failure develops, as autologous rescue after chemotherapy in the event of leukemic transformation, or as targets for gene therapy. Eight patients with Fanconi anemia were mobilized with 10 microg/kg per day of granulocyte colony-stimulating factor (median, 10 +/- 4 days) to determine the feasibility of collecting peripheral blood stem cells for future use. Six patients achieved a peripheral blood CD34+ count of > or = 6/microL and underwent apheresis. The collection goal was 2 x 10(6) CD34+ cells/kg based on a predicted weight 5 years from the date of collection. A mean of 2.6 +/- 0.9 x 10(6) CD34+ cells/kg of the weight at the time of collection were collected, which corresponded to 1.9 +/- 0.4 x 10(6) CD34+ cells/kg of the target weight. The collections required a mean of 4 +/- 3 days (range, 2-8 days) of apheresis. Six of the 8 subjects had > or = 1 x 10(6) CD34+ cells/kg cryopreserved based on both actual and target weights, and 4 subjects had > or = 2 x 10(6) CD34+ cells/kg cryopreserved based on the target weight. These results suggest that some patients with Fanconi anemia can have adequate numbers of CD34+ cells mobilized and collected from the peripheral blood prior to the onset of severe bone marrow failure, but they may require an extended mobilization and multiple days of collection.     

Transplantation of allogeneic peripheral blood stem cells after myeloablative treatment of a patient in blastic crisis of chronic myelocytic leukemia

A 48-year-old man in blastic crisis of chronic myelocytic leukemia received a transplant of allogeneic peripheral blood stem cells. The donor was his HLA-identical sister, who refused to donate bone marrow cells, but agreed to donate peripheral blood stem cells. The patient received standard transplant conditioning with cyclophosphamide (120 mg/ kg) and busulfan (16 mg/kg). Peripheral blood stem cells were mobilized with granulocyte colony stimulating factor and collected by apheresis. After transplantation, the white blood cell count and the result of microscopic analysis of the bone marrow became normal, and the leukocyte karyotype became 46XX. DNA fingerprinting showed complete chimerism. Graft-versus-host disease was suppressed with cyclosporine and methyl-prednisolone. The patient died of recurrence of leukemia on day 102+. © 1994 Wiley-Liss, Inc.     

Has allogeneic stem cell cryopreservation been given the 'cold shoulder'? An analysis of the pros and cons of using frozen versus fresh stem cell products in allogeneic stem cell transplantation

Donor stem cells for allogeneic transplant traditionally are collected and transfused 'fresh' into the recipient on the day of transplant; alternatively such cells can be collected in advance and cryopreserved until needed. Most centers favor the former approach based on theoretical concerns that cryopreservation and thawing may worsen clinical outcomes. Limited published data from single institution retrospective studies show no significant impairment of engraftment or reduced day 100 survival for cryopreserved bone marrow recipients. There are no reported outcomes for recipients of cryopreserved peripheral blood allografts. Use of cryopreserved stem cells is associated with a higher incidence of adverse events (transfusion reactions, bacterial graft contamination and collection of grafts which are not utilized). Conversely, use of cryopreserved grafts introduces a greater flexibility into a stressed healthcare system and results in a more streamlined experience for the donor. Some data suggest that transplantation with a cryopreserved product may lower the incidence of acute graft-versus-host disease. We compare the pros and cons of using 'fresh' versus cryopreserved stem cell products for allogeneic transplantation and suggest that the current standard of using 'fresh' products may not be warranted. We also suggest future areas of exploration to better elucidate this issue.     

Successful engraftment of haploidentical stem cell transplant for familial haemophagocytic lymphohistiocytosis using both bone marrow and peripheral blood stem cells

Familial haemophagocytic lymphohistiocytosis (HLH) is a disease with a very poor prognosis unless patients receive a bone marrow transplant. It is often difficult to find an HLA-matched donor and haploidentical familial donors may be considered. The main complication of this type of transplant is graft rejection. We describe a patient with familial HLH who received a haploidentical transplant using both mobilized peripheral blood and bone marrow stem cells in an attempt to overcome graft rejection by increasing the stem cell dose. The peripheral blood stem cell inoculum was CD34 enriched using a Cellpro column and T-cell depleted by Campath-1M, the patient received conditioning for a matched sibling donor transplant with the addition of Campath 1G. There was rapid and full engraftment and the patient remains disease free at 5 months. This technique may be applicable for other fatal inborn errors in the absence of an HLA-matched donor.     

Stem cell component therapy: supplementation of unmanipulated marrow with CD34 enriched peripheral blood stem cells

Eleven patients with hematologic malignancies and two with aplastic anemia were treated using unmanipulated marrow and immunoselected CD34+ blood cells. Donors began G-CSF (10 microg/kg) injections 1 day after undergoing bone marrow harvest. Blood stem cells were collected on day 5 of G-CSF. Peripheral blood lymphocytes were depleted via CD34-positive selection. If, after marrow and blood harvest, less than 2.0 x 10(6) CD34 cells/kg were mobilized, leukapheresis was repeated on day 6. Median time to an absolute neutrophil count greater than 500 microl was day 10; transfusion-independent platelet count greater than 20,000/microl was day 13; average hospital discharge was day 14; and average inpatient hospital charges were 101,870 US dollars. Acute GVHD grade II occurred in five of 13 patients. No patient developed grade III or IV acute GVHD. At a median follow-up of 10 months, no patient has developed extensive chronic GVHD. Allografts of unmanipulated bone marrow supplemented with G-CSF-mobilized and CD34 immunoselected blood cells may prevent an increased risk of GVHD while preserving the rapid engraftment kinetics of peripheral blood. Supplementation of marrow with CD34 enriched blood cells appears to result in rapid engraftment, early hospital discharge, lower inpatient charges, decreased regimen-related toxicity, and no apparent increase in GVHD.     

Transplantation with selected autologous peripheral blood CD34+Thy1+ hematopoietic stem cells (HSCs) in multiple myeloma: impact of HSC dose on engraftment, safety, and immune reconstitution

OBJECTIVE: The aims of our study performed in myeloma were to evaluate the performance and the safety of Systemix's high-speed clinical cell sorter, to assess the safety and efficacy of deescalating cell dose cohorts of CD34+Thyl+ hematopoietic stem cells (HSCs) as autologous grafts by determining engraftment, and to assess the residual tumor cell contamination using polymerase chain reaction (PCR) amplification assays of patient-specific complementarity determining region III (CDR III) analysis for residual myeloma cells. MATERIALS AND METHODS: The clinical trial was performed in 31 multiple myeloma patients, using purified human CD34+Thyl+ HSCs mobilized from peripheral blood with cyclosphosphamide and granulocyte-macrophage colony-stimulating factor to support a single transplant after high-dose melphalan 140 mg/m2 alone (cohort 1) and with total body irradiation (TBI) (cohorts 2-5) after an HSC transplant cell dose de-escalation/escalation design. RESULTS: Twenty-three patients were transplanted. Engraftment data in the melphalan + TBI cohorts confirmed that HSC doses above the threshold dose of 0.8 x 10(6) CD34+Thy1+ HSCs/ kg provided prompt engraftment (absolute neutrophil count >0.5 x 10(9)/L day 10; platelet count >50 x 10(9)/L day 13). A higher rate of infections was observed in the early and late follow-up phases than usually reported after CD34+ selected or unselected autologous transplantation, which did not correlate with the CD34+Thy1+ HSC dose infused. Successful PCR for CDR III could only be performed in five patients on initial apheresis product and final CD34+Thy1+ HSC product and showed a median tumor log reduction >3.12. CONCLUSIONS: CD34+Thy1+ HSCs are markedly depleted or free of detectable tumor cells in multiple myeloma and are capable of producing fast and durable hematopoietic reconstitution at cell doses >0.8 x 10(6) CD34+Thy1+ HSCs/kg. The delayed immune reconstitution observed is not different from that described in unselected autologous bone marrow and peripheral blood mononucleated cells transplants in multiple myeloma and may be corrected by addition of T cells either to the graft or to the patient in the posttransplant phase.     

Peripheral stem cell transplantation in a child with amegakaryocytic thrombocytopenia

Congenital amegakaryocytic thrombocytopenia (CAMT) is an unusual cause of thrombocytopenia without radial or other congenital anomalies in the newborn. Generalized bone marrow dysfunction developing later in life has been reported. We present a 13-month-old girl who was diagnosed as having congenital amegakaryocytic thrombocytopenia and was successfully treated with allogeneic peripheral stem cell transplantation (PSCT) from her fully matched sibling donor. The neutrophil engraftment was on post transplant day 12 and platelet engraftment was on day 14. Her last hemogram revealed platelets of 168 x 10(9)/l 20 months post transplant.     

Allogeneic blood stem cell transplantation for refractory leukemia and lymphoma: potential advantage of blood over marrow allografts [see comments]

Peripheral blood stem cells (PBSCs) have been used rarely for allogeneic transplantation because of concerns regarding graft failure and graft-versus-host disease (GVHD). We evaluated the results of allogeneic PBSC transplantation (allo-PBSCT) in 9 patients with refractory leukemia or lymphoma receiving myeloablative therapy followed by allo-PBSCT from an HLA-identical sibling donor. Three patients had relapsed 11 to 21 months after allogeneic bone marrow transplantation (allo-BMT) and underwent allo-PBSCT using the same donor. Six patients received PBSCs as their initial allogeneic transplant. Filgrastim-mobilized PBSCs were collected from the donors in 3 to 4 aphereses and cryopreserved. The apheresis collections contained a median nucleated cell count of 16.5 x 10(8)/kg (range, 10.8 to 28.7 x 10(8), 10.7 x 10(6) CD34+ cells/kg (range, 7.5 to 22.5 x 10(6)), and 300.0 x 10(6) CD3+ cells/kg (range, 127.8 to 1,523.2 x 10(6)). The median recovery of CD34+ progenitor cells after freezing, thawing, and washing was 106.4% (range, 36.7% to 132.0%). All patients received filgrastim posttransplant through engraftment, and cyclosporine and methylprednisolone were used for GVHD prophylaxis. Neutrophil recovery to greater than 0.5 x 10(9)/L and greater than 1.0 x 10(9)/L occurred at a median of 9 (range, 8 to 10) and 9 days (range, 8 to 11) posttransplant, respectively, which was similar to historical controls after allo-BMT and granulocyte colony-stimulating factor therapy. Platelets recovered to greater than 20 x 10(9)/L and greater than 50 x 10(9)/L at a median of 12 (range, 8 to 25) and 15 days (range, 11 to 59), respectively, which was significantly more rapid than for the controls (P < .01). Donor cell engraftment was documented by cytogenetics, fluorescence in situ hybridization, and/or restriction fragment length polymorphisms with longest follow-up of 283 + days. Three patients developed grade 2 acute GVHD involving only the skin. Three of five evaluable patients show limited chronic GVHD. Cryopreserved, filgrastim-stimulated allogeneic PBSCs may be a suitable alternative to allogeneic marrow for transplantation with the advantage of more rapid platelet recovery. Acute GVHD was minimal despite the infusion of 1 log more CD3 cells than with marrow allografts. Further studies are required to assess long-term risks of chronic GVHD.     

Allogeneic CD34-enriched peripheral blood stem cell transplantation in a patient with paroxysmal nocturnal haemoglobinuria

Paroxysmal nocturnal haemoglobinuria (PNH) is an acquired clonal disorder of haematopoietic stem cells associated with a somatic mutation in the phosphatidylinositol glycan complementation class A (PIG-A) gene. The only curative option is an allogeneic stem cell transplant (SCT), although treatment is hazardous. A 46-year-old male patient with PNH and obvious signs of severe, progressive haemolysis was transplanted in July 2002 with highly purified CD34 T-cell depleted peripheral blood stem cells from his HLA-identical brother. Prior to transplantation, the PNH was resistant to immunosuppressive therapy. The patient received 6.1 x 10(6)/kg bodyweight CD34-positive cells with a proportion of CD3-positive cells of 0.81 x 10(4)/kg bodyweight. After engraftment, 12 days post transplant (neutrophils>1.0/nl) the patient's physical condition steadily improved and parameters of haemolysis decreased. No glycophosphatidylinositol-deficient cells in peripheral blood could be detected by flow cytometry 40 and 100 days after transplant. We conclude that PNH may be cured by allogeneic CD34-enriched SCT from a sibling donor attempting to avoid acute GVHD and to reduce cumulative organ toxicity by using this transplantation modality.     

Confirmation of bone marrow engraftment by detection of M/N blood group antigens on erythroblasts in erythroid bursts

In order to confirm erythroid engraftment, we examined the changes in blood group antigens expressed on erythroblasts in the haematopoietic colonies of a bone marrow transplant recipient. A 44-year-old female with acute myelogenous leukaemia underwent an allogeneic bone marrow transplantation from her sister donor. Prior to the transplantation, the blood groups of both recipient and donor were analysed, and their M/N groups found to differ, the former being MN and the latter N. Bone marrow mononuclear cells were obtained from the patient on day 21 after bone marrow transplantation and cultured in semi-solid medium. Erythroblasts were collected from the erythroid bursts that had formed, and were subjected to flow cytometry using monoclonal anti-M and anti-N. Anti-N reactive cells accounted for 99.2% of those in the erythroid bursts, while only 0.3% of these cells were anti-M reactive. MN type erythrocytes in the recipient's peripheral blood had been replaced by N type and only 2.0% of erythrocytes were anti-M reactive on the 70th day after BMT. These erythroblasts and erythrocytes were phenotypically N, and originated from the donor haemopoietic stem cells with the success of bone marrow engraftment. From our findings, it appears that the M/N blood group antigens were produced by the erythroid cells themselves.     

Correction of infantile agranulocytosis (Kostmann's syndrome) by allogeneic bone marrow transplantation

Allogeneic bone marrow transplantation has been unsuccessful as therapy for genetically determined bone marrow disorders. In patients prepared for transplantation with drugs alone long-term hematopoietic engraftment is not achieved due to the overgrowth of the infused donor bone marrow cells by residual recipient hematopoietic stem cells. Utilizing a combination of total body irradiation and antihuman thymocyte serum, the successful eradication of the abnormal hematopoietic stem cells of patients with the Wiskott-Aldrich syndrome and now infantile agranulocytosis has been achieved. Following preparation with total body irradiation and antihuman thymocyte serum a 20 month old patient with infantile agranulocytosis has complete donor hematopoietic and lymphoid engraftment one year after a histocompatible allogeneic bone marrow transplant. Prior to transplantation, this patient had no circulating or bone marrow granulocytes; following transplantation he has normal numbers of circulating granulocytes with normal in vivo and in vitro function. This therapeutic result demonstrates that genetic disorders of myeloid function can be corrected by allogeneic bone marrow transplantation following preparation with total body irradiation and antihuman thymocyte serum, and suggests that infantile agranulocytosis is due to an intrinsic defect of the pluripotent hematopoietic stem cell and not to a micro-environmental defect.     

Addition of peripheral blood stem cells collected without mobilization techniques to transplanted autologous bone marrow did not hasten marrow recovery following myeloablative therapy.

A randomized prospective trial was conducted to determine if the addition of cryopreserved autologous peripheral blood stem cells (PBSC) collected without mobilization techniques to autologous cryopreserved bone marrow for patients receiving an autologous bone marrow transplant (ABMT) affected the time to marrow function recovery. Thirty-five evaluable patients with various malignancies were studied. Sixteen received PBSC + ABMT and 19 received ABMT alone. The PBSC were collected with 4 h leukapheresis procedures on 3 consecutive days. No manipulations to increase the number of circulating stem cells were used during the collections. The median time to recover 0.5 x 10(9)/l circulating granulocytes was 20 days after transplantation in the ABMT group and 27 days in the PBSC + ABMT group (p = 0.12). The median time to recover 20 x 10(9)/l platelets was 22 days after transplantation in the ABMT group and more than 27 days in the PBSC + ABMT group (p = 0.29). The day of discharge from the hospital was earlier for the ABMT group (median 29 days) than the PBSC + ABMT group (median 35 days, p = 0.03). We did not find that the addition of non-mobilized PBSC to infused autologous marrow accelerates marrow recovery.     

Serum interleukin-3 levels following autologous or allogeneic bone marrow transplantation: effects of T-cell depletion, blood stem cell infusion, and hematopoietic growth factor treatment

Engraftment of marrow following autologous or allogeneic bone marrow transplantation (BMT) may be influenced by quantity and function of stem cells. T lymphocytes, supporting microenvironmental cells, and hematopoietic growth factors (HGF). To elucidate the physiologic role of interleukin-3 (IL-3) in the engraftment process, serum IL-3 levels were measured in over 400 samples from 77 transplant recipients before and for up to 3 weeks following transplantation using a novel enzyme- linked immunoabsorbent assay (ELISA) with a sensitivity of > or = 78 pg/mL. Thirty-seven patients received two to three log T-cell-depleted allografts. In the remaining 40 patients (18 autologous marrow, 12 allogeneic marrow, and 10 autologous peripheral blood [PB] stem cell), T cells were not depleted (non-TCD) from the grafts. A burst of IL-3 (peak levels, 1,500 to 6,000 pg/mL) was detected in the immediate posttransplant period between day 0 and day 14 in all non-TCD recipients and in 21 of 37 (57%) of TCD recipients. A strong inverse relationship between IL-3 levels and absolute neutrophil count (ANC) was observed in both non-TCD recipients (r = -.796) and in TCD recipients (r = -.897). However, both peak IL-3 levels and mean IL-3 levels from day 0 through 14 were significantly lower in TCD recipients compared with either autologous or unmodified allogeneic marrow recipients (P < .01). The lowest peak or mean day 0 through 14 IL-3 levels were observed in matched related recipients undergoing the most aggressive (2.5 to 3.0 log) T-cell-depleted BMT. Autografted patients receiving blood stem cell transplants alone or posttransplant granulocyte colony-stimulating factor (G-CSF) or granulocyte-macrophage colony stimulating factor (GM-CSF) also had significantly lower peak IL- 3 levels (P < .01). In patients receiving TCD grafts, administration of antithymocyte globulin (ATG) posttransplant significantly increased peak IL-3 levels compared with patients not treated with ATG (P < .04). This study shows that endogenous release of IL-3 is strongly associated with myeloid engraftment and inversely related to ANC. Removal of T lymphocytes from donor marrow or acceleration of engraftment by use of stem cells or growth factors appears to blunt the endogenous release of IL-3 whereas use of ATG posttransplant increases IL-3 release.     

Large scale purification of human blood CD34+ cells from cryopreserved peripheral blood stem cells, using a nylon-fiber syringe system and immunomagnetic microspheres

Isolation of large numbers of human peripheral blood CD34+ cells could lead to therapeutic applications, including purging of malignant cells from blood cell transplantations, purging of T cells from allogeneic bone marrow, and even blood cell transplantation. This procedure has limitations if there are not sufficient numbers of progenitor cells in the leukapheresis concentrates available for selection after detection of tumor cells in apheresis products. Use of frozen/thawed peripheral blood mononuclear cell (PBMC) samples would make feasible pooling of two or even more stem cell harvests collected at different time points and the total number of CD34+ progenitor cells available would increase. We established an efficient method for purification of CD34+ cells from cryopreserved apheresis products, using a nylon-fiber syringe system and immunomagnetic microspheres. We compared purity, recovery rate and clonogenicity of CD34+ cells purified from fresh (n = 22) and cryopreserved apheresis products (n = 14), using a nylon-fiber syringe system and immunomagnetic microspheres. The purity of CD34+ cells from cryopreserved products was less than that from fresh products (85.9 +/- 14.4% vs 94.6 +/- 10.0%), but the recovery rate of CD34+ cells and colony-forming cells was comparable between fresh and cryopreserved products. One patient underwent grafting with peripheral blood CD34+ cells selected after freezing, with good success. Therefore, these cells are capable of rapidly reconstituting hematopoiesis after high-dose chemotherapy. Bone Marrow Transplantation (2000) 26, 787-793.     

New strategies in allogeneic stem cell transplantation: immunotherapy using irradiated allogeneic T cells

Recipients of T cell-depleted allogeneic bone marrow transplants have increased risks of relapse and graft rejection. The addition of donor T cells to the TCD allograft will decrease the risk of graft rejection but will increase the risk of graft-versus-host disease (GVHD). Relapse of leukemia or lymphoma following allogeneic bone marrow transplantation can be successfully treated with post-transplant infusions of donor lymphocytes. A relatively small number of donor T cells can have a profound anti-tumor effect and facilitate engraftment, but has an unpredictable potential for severe GVHD. An alternative to using viable immunocompetent donor immune cells to facilitate engraftment and to treat relapsed patients are donor lymphocytes that have been treated to limit their ability to proliferate and cause GVHD. T cells treated with irradiation retain cytotoxic activity against tumor cells and host immune cells. We have tested the hypothesis that allogeneic donor T cells treated with low-dose irradiation will facilitate engraftment and mediate an anti-leukemia effect in a mouse model of bone marrow transplantation. Multiple infusions of irradiated allogeneic donor lymphocytes in the peri-transplant period had graft-enhancing activity without resulting in GVHD. Murine recipients of irradiated allogeneic splenocytes and allogeneic bone marrow had stable donor-derived hematopoiesis without a significant contribution of irradiated donor cells to the T cell compartment. Removing T cells from the allogeneic splenocytes prior to irradiation largely eliminated their graft facilitating activity. Based upon the promising results of the pre-clinical murine studies, we initiated a phase I clinical trial of multiple infusions of irradiated allogeneic lymphocytes in patients who had relapsed after allogeneic BMT. Of 12 patients treated to date on this study, three have shown objective responses of their leukemia or lymphoma to multiple infusions of irradiated donor lymphocytes. We have initiated a new phase I clinical study to test the efficacy of multiple infusions of irradiated allogeneic cytotoxic T cells to facilitate engraftment in allogeneic transplantation. Successive cohorts of patients will be transplanted with allogeneic stem cells alone, or a combination of allogeneic stem cells and increasing numbers of irradiated allogeneic T cells. Irradiated allogeneic lymphocytes that retain short-term allo-specific cytotoxicity and lack the potential for clonal expansion in vivo can be considered as a novel form of immunotherapy with defined pharmacokinetics.     

异基因造血干细胞移植后的嵌合状态分析

目的研究异基因外周血造血干细胞移植（allo-PBSCT）后T淋巴细胞和粒细胞嵌合状态与疾病复发、移植物被排斥和移植物抗宿主病（GVHD）等的关系.方法21例HLA完全相合allo-PBSCT患者,流式细胞仪分选出外周血粒细胞、T淋巴细胞,分别进行短串联重复片段（STR）-PCR扩增.结果移植后7 d时17/21例患者T淋巴细胞的植入程度高于粒细胞,供者嵌合比例（DC）分别为60%（15%～76%）和0%（0%～40%）.除去移植后28 d复发且T淋巴细胞一直为混合嵌合（MC）1例,其余20例T淋巴细胞达到完全嵌合（CDC）的中位时间是21（14～102）d,粒细胞为14 d.T淋巴细胞比粒细胞更早植入,但达到CDC的时间较粒细胞晚.7例在疾病复发或移植物被排斥时,T淋巴细胞比粒细胞更早出现DC的下降,其中4例患者仅表现为T淋巴细胞出现DC的下降,而全骨髓细胞和粒细胞仍为CDC或无明显下降,骨髓象检查未见异常.而在减量、停用免疫抑制剂或供者淋巴细胞输注后,治疗有效的4例患者T淋巴细胞逐渐由MC变为CDC,并有3例在转变过程中出现急性GVHD.结论allo-PBSCT后进行白细胞亚群,尤其是T淋巴细胞的嵌合状态检测可以比全血或全骨髓样本更早发现供者细胞的植入、疾病复发或移植物被排斥,及时采取相应的免疫干预措施,提高移植成功率.