Prospective randomised concurrent comparison of the COBE spectra version 4.7, COBE spectra version 6 (Auto PBSCtrade mark), and haemonetics MCS+ cell separators for leucapheresis in patients with haematological and non haematological malignancies

Optimization of leukocyte collection and monocyte isolation for dendritic cell culture

Leukapheresis is the method of choice to collect monocytes for dendritic cell (DC) culture. Improvement of cell separators and cell collection software have enabled the collection of 10(9) monocytes for the generation of monocyte-derived DCs, which is sufficient to prepare a DC vaccine series. However, leukapheresis works with the technique of differential centrifugation which is not applicable to selectively collect mononuclear cells of similar density. After leukapheresis, thus, additional preparation steps are required to isolate and enrich the desired monocyte population. The cell isolation and cultivation techniques depend on the quality of the original leukocyte harvest due to the monocyte yield and the content of residual erythrocytes and platelets. Monocyte elutriation from the leukapheresis product shows a high monocyte recovery of 80%. However, only 30% of the isolated monocytes can be developed into mature DCs. The factors responsible for DC maturation and the development of different DC subsets are the subject of current research.

Mobilization and collection of peripheral blood progenitor cells for transplantation

Bone marrow transplantation gradually expanded as a treatment modality for various malignant and non malignant disease conditions. Since the discoveries of the potential of Peripheral Blood Progenitor Cells (PBPC) in the hematopoietic reconstitution mid 1980s and early 1990s PBPC gradually replaced bone marrow as the preferred source of stem cells. The introduction of hematopoietic cytokines that can mobilize large number of progenitors into circulation accelerated PBPC usage. Technological advancements in the apheresis instrumentation greatly helped in the conversion from marrow to PBPC. PBPC collection is less painful, less expensive and transplant with PBPC results in faster hematological recovery than with marrow. Almost all of the autologous transplants are currently performed with PBPC and a similar trend is seen with the allogeneic transplants. The progenitor cell mobilization regimen for autologous patients can be cytokines alone or cytokines combined with chemotherapy. In the majority of the patients the required minimal cell dose of 2.5-5.0 x 10(6)/kg CD34+ cells can be collected in one or two apheresis collections. A few of autologous transplant patients who mobilize poorly require several collections. Allogeneic donors are generally mobilized with daily subcutaneous injections of G-CSF 10 microg/kg for 5 days. The PBPC are collected in one or two apheresis procedures. The side effects of G-CSF are generally mild to moderate; however rare serious reactions including rupture of the spleen have been reported. The collection of PBPC in pediatric patients poses additional challenges yet an adequate dose of cells can be collected with the available apheresis instrumentation. The apheresis collection procedures are safe with no serious adverse consequences. Future scientific advancements may expand the use of PBPC for other clinical application in addition to the current use for hematological reconstitution.

Analysis of factors affecting PBPC collection in low-weight children with malignant disorders

BACKGROUND

PBPC collection in children weighing </=25 kg is hampered by technical and clinical problems related to vascular access, low total blood volume, anticoagulation, side effects, and psychological impact. The aim of this study was to analyze several clinical and technical factors, other than pre-apheresis CD34(+) count, that may affect PBPC collection in these low-weight children.

METHODS

Data from 88 leukaphereses performed in 45 children were analyzed, including pre-apheresis CD34(+) cell count, COBE Spectra software (version 4.7 versus 6.0), apheresis volume [standard versus large-volume leukapheresis (LVL)] and patient's diagnosis, age, weight and sex.

RESULTS

The median number of PBPC collected was 6.68 mononuclear cells (MNC)x10(8)/kg (range 2.36-19.05) and 1.69 CD34(+) cellsx10(6)/kg (range 0.08-13.79). Multivariate analysis showed that factors independently associated with the CD34(+) cell yield per apheresis were pre-apheresis CD34(+) cell count (P<0.001), diagnosis (P=0.008) and apheresis volume (P=0.009). Recruitment of CD34(+) cells was also independently affected by the apheresis volume, being higher in the LVL group (P=0.008).

DISCUSSION

We have demonstrated that, apart from the well-known influence of the pre-apheresis CD34(+) cell count, two other factors have a major impact on the CD34(+) cell yield: patient's diagnosis and apheresis volume. In addition, taking into account that side effects were mild and tolerable, we have confirmed that LVL is a safe and effective procedure in children </=25 kg, and that AutoPBSC software could be reliably used in these patients, provided that an experienced team performs the procedure.