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PURPOSE (1) To study the ability of mobilized peripheral-blood progenitor cells (PBPC) collected in a single large-volume leukapheresis performed on a predetermined date to accelerate engraftment after high-dose cyclophosphamide and thiotepa; (2) to establish the minimum dose of PBPC associated with early engraftment; and (3) to identify parameters predictive of collection of large numbers of PBPC. PATIENTS AND METHODS Twenty-three patients with breast cancer received cyclophosphamide (4 g/m2) and granulocyte-macrophage colony-stimulating factor ([GM-CSF] 5 micrograms/kg/d x 15 days) for PBPC mobilization. A single leukapheresis was performed 15 days after cyclophosphamide administration. Then, patients received high-dose cyclophosphamide and thiotepa followed by reinfusion of PBPC and 4-hydroperoxycyclophosphamide (4HC)-purged bone marrow. PBPC concentration was measured in serial peripheral-blood samples and in the leukapheresis product. Correlation analysis between PBPC dose and engraftment and between leukapheresis yield and patient characteristics was attempted. RESULTS A single leukapheresis processed a median 36 L (range, 24 to 46) blood and collected 5 x 10(6) CD34+ cells/kg (< 0.3 to 24) and 6.2 x 10(5) colony-forming units granulocyte-macrophage (CFU-GM)/kg (< 0.001 to 29). All sixteen patients (70%) reinfused with > or = 2.9 x 10(6) CD34+ cells/kg reached a level of greater than 1,000 leukocytes/microL by day 13 and greater than 50,000 platelets/microL by day 15. All of these patients had a percentage of peripheral-blood CD34+ cells > or = 0.5%, and all but one, a level of greater than 100,000 platelets/microL, on the day of leukapheresis. The bone marrow CD34+ cell percentage at study entry predicted the number of CD34+ cells collected after PBPC mobilization (R2 = .42, P = .002). All patients with > or = 2.5% bone marrow CD34+ cells experienced early engraftment. CONCLUSION Reinfusion of PBPC collected in a single leukapheresis accelerates engraftment in the majority of patients. Pretreatment bone marrow CD34+ cell content determines PBPC mobilization capacity and may help select hematopoietic rescue strategies.

Two patients with multiple myeloma in relapse after allogeneic BMT received donor lymphocyte infusions (DLI) but later required chemotherapy for treatment of myeloma-related complications. In both patients, recovery from chemotherapy-induced aplasia was accompanied by manifestations of graft-versus-host reactions. The first patient developed grade II acute GVHD and a complete remission which has lasted >22 months. The second patient developed grade III acute GVHD but died with co-existing GVHD and extensive extramedullary myeloma. These results demonstrate that chemotherapy does not nullify the ability of donor lymphocytes to mediate graft-versus-host reactions.

The use of peripheral blood progenitor cells (PBPC) for hematopoietic rescue after high-dose chemotherapy is limited by the number of leukaphereses required to collect an adequate number of hematopoietic progenitors. To optimize the collection of PBPC, we evaluated a single large-volume leukapheresis protocol with citrate anticoagulation. A group of 23 patients received cyclophosphamide (4 g/m2) and GM-CSF (5 micrograms/kg/day for 15 days) as PBPC mobilization, with a single outpatient 6 h leukapheresis performed on the COBE Spectra 15 days later. Citrate (0.190 mmol/ml) was infused at 1.2 ml/L of blood/minute with a whole blood to citrate ratio between 17:1 and 25:1. Calcium chloride (50 mM) was administered at a citrate to calcium molar ratio between 10:1 and 5:1 to prevent hypocalcemia. A median 36.6 L (range 24.4-46.4) blood was processed using 338 mM citrate (269-473) and 50 mM calcium (25-75). A median 5 x 10(6) CD34+ cells/kg (0.3-24) and 6.2 x 10(5) CFU-GM/kg (0.001-29) were collected, representing 5.6 and 5.9 more PBPC, respectively, than were in circulation at the initiation of leukapheresis. We conclude that a 6 h large-volume leukapheresis following cyclophosphamide and GM-CSF mobilization is safe, can recruit hematopoietic progenitors into the circulatory compartment, and allows the collection of high numbers of PBPC in a single procedure.

Twenty-five patients with major ABO blood group incompatibility between donor and recipient underwent allogeneic bone marrow transplantation using erythrocyte depletion of the bone marrow infusate prior to administration. Over 95% of the original erythrocyte content of the marrows was removed, while retaining 75% of the mononuclear cell content and 57% of the granulocyte-monocyte colony-forming units. Recipients, well hydrated and premedicated with corticosteroids, diphenhydramine, and mannitol, tolerated infusions well. The frequency of engraftment, rate of recovery of peripheral blood leukocytes, granulocytes, and platelets, and the incidence of graft-versus-host disease was similar to that observed following ABO blood group compatible bone marrow transplantation. Erythroid development following ABO blood group incompatible transplantation was significantly impaired until hemagglutinins fell to 1:4 or lower, at which time recovery of erythrocytes was detected in the peripheral blood. The erythrocyte hypoplasia associated with incompatible hemagglutinins was temporary. Erythrocyte purging is a safe and effective technique to perform bone marrow transplantation across major ABO blood group incompatibilities.