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At least 19 recordsLinked to original sources
PubMed1978

Cell separation, cell differential and granulocyte colony frequency in polycythemia vera.

In seven patients with polycythemia vera, the agar colony growth of bone marrow total nucleated cell suspensions and of the cell fractions obtained with an albumin discontinuous density gradient were studied. In one patient, the density distribution of colony-forming units in culture (CFUc) before and after alkylating treatment was evaluated and cell differentials on smears obtained from each density fraction were determined. A high percentage of low density CFUc compared with the total CFUc population and with that in the normal control subjects in the same density fractions was observed.

Bone Marrow↗
PubMed1991

[Stem cell separation with different cell separators].

For some years, there has been an increasing success in transplanting peripheral blood stem cells (PBSC) instead of autologous bone marrow in patients suffering from different malignancies. While collecting PBSC for autologous transplantation, we compared four different separation techniques and three different cell separators (COBE Spectra, Fresenius AS 104, Haemonetics V50) routinely used for platelet production. Our results suggest that continuous flow separators seem to have some advantage over discontinuous flow machines in harvesting PBSC.

Blood Cell Count↗
PubMed1991

[Optimizing cell separation with the Cell Separator AS-106].

Seventeen different separation protocols based on more than 1100 thrombocytaphereses were tested. Twelve of these are reported on in this study. It became apparent that the most important variable is the centrifugation speed (1900 rpm at a blood flow of 50 ml/min). This made it possible to collect 3.5 to 3.8 x 10(11) thrombocytes (approx. 60% extraction efficiency) from 3.15 l blood. Further optimization of this procedure is desirable, since 10% of the thrombocytes still remain in the separation chamber. However, our optimization work was successful as far as the reduction of leukocyte and erythrocyte contamination is concerned, which ultimately resulted in leukocyte and erythrocyte contamination of about 1 x 10(7).

Blood Component Transfusion↗
PubMed1991

[Tumor cell separation by cell saver and membrane filter passage].

Definite suspensions of malignant cells from three human tumor cells lines (bladder, prostate and renal cell carcinom) were passed through a cell saver (Althin Mediplast) and a leucozyte removal filter (PALL RC 100) under standard conditions. The examination of the solutions did not detect any malignant cells at all. If investigations with malignant cells in the blood will confirm these results, the use of intraoperative autotransfusion in urological tumor surgery would be possible.

Blood Transfusion, Autologous↗
PubMed1990

[Comparison of thrombocyte concentrates of the cell separator AS 104 with preparations of the cell separator CS 3000 (Fenwal)].

Platelet concentrates of the cell separator AS 104 (Fresenius) are compared with those of the cell separator CS 3000 (Fenwal). At each cell separator two platelet preparation protocols and at CS 3000 additionally a WBC preparation protocol was analysed. Platelet counts before and after cellapheresis as well as separation efficiencies show no significant differences between the separation protocols (A, B) and the two cell separators. Platelets of varying volumes show different separation efficiencies. While in WBC concentrates the separation efficiencies of platelets continuously increase from small (2fl) to large (20 fl) platelets, the efficiencies in platelet concentrates decrease in volume range 2 fl-8 fl, and increase in range 8 fl-20 fl. There are no differences between the cell separators. The efficiencies of platelets with 2 fl and 4 fl volumes differ significantly (p less than 0.001) between the protocols A and B of AS 104. After WBC-donation, platelet loss of donors corresponds with platelet yields of the concentrates for the platelet volume range 2 fl-20 fl. Compared with the calculated platelet loss of donors after platelet donation more small platelets with 2 fl-8 fl volumes are found in platelet concentrates. The yields of platelets with 10 fl-20 fl volumes are in accordance with donor's platelet loss.

Blood Transfusion↗
PubMed1976

Membrane surface properties other than charge involved in cell separation by partition in polymer, aqueous two-phase systems.

When aqueous solutions of dextran and of poly-(ethylene glycol) are mixed above certain concentrations, immiscible, liquid two-phase systems are obtained which are useful for separating cells by partition. Some salts partition unequally between the phases, giving rise to an electrostatic potential difference between them. Partition of cells has therefore been thought to depend predominantly on membrane charge. We now report two instances in which membrane charge either does not determine or is not the main determinant of cell partition. (A) Cell partition coefficients in phase systems approaching the critical point (the component concentrations below which a homogeneous solution occurs) increase, even in phase systems in which the phase potential difference is practically zero. Furthermore, in such systems, the partition coefficient of (human) erythrocytes is not reduced by complete removal of sialic acid. (B) Rat and mouse erythrocytes have sizable partition coefficients in a phase system away from the critical point with no potential difference between the phases. Cell surface interaction with the polymers is probably responsible for cell partition in these cases. Partition studies on erythrocytes from nine mammalian species in phases near the critical point with and without electrostatic potential differences reveal major species-specific differences in the membrane charge/noncharge components. A correlation has been found, in phases near the critical point that have essentially no electrostatic potential difference, between partition coefficient and the ratio of poly/monounsaturated fatty acids in the membranes of red cells from different species. Our present results thus provide parameters for the separation of cells by partition in addition to or instead of membrane charge depending on the polymer and salt composition and concentration selected.

Animals↗
PubMed1990

A large-scale magnetic separator for selective cell separations with paramagnetic microbeads.

An improved magnetic separator has been developed for use in large-scale cell separations. This separation method uses paramagnetic microbeads coated with antibodies that selectively bind to target cells. The magnetic separator attracts the microbead-target cell aggregates and holds these aggregates at its surface while the suspending fluid and nontarget cells flow past. The optimum separator design was determined to be two magnetic assemblies in series along with a peristaltic pump. The assemblies consist of neodymium-iron-boron magnet bars sandwiched between steel bars (magnetic pole pieces). The size and pole spacing of the two magnetic assemblies are designed to be different, so that the first assembly, which captures greater than 99.99% of the microbeads, has good magnetic reach-out and a high magnetic holding force at its surface, while the second assembly has an even higher magnetic holding force at its surface. Studies show that the separator can remove 1 x 10(10) microbeads from a suspension of red blood cells processed at a flow rate of 9 ml/min, so that no microbeads are detected in the effluent.

Animals↗
PubMed1986

Synthesis and application of a poly(ethylene glycol)-antibody affinity ligand for cell separations in aqueous polymer two-phase systems.

The possibility of producing biospecific affinity ligands for separating cells in two polymer aqueous phase systems on the basis of cell surface antigens was investigated. Rabbit anti-human erythrocyte IgG was reacted with cyanuric chloride-activated monomethyl poly(ethylene glycol) (PEG) fractions (molecular weights approximately 200, 1900, and 5000) at various molar ratios of PEG to protein lysine groups. The partition coefficient of the protein in a Dextran/PEG two-phase system increased with increasing degree of modification and increasing PEG molecular weight. There was a concomitant loss in ability to agglutinate human erythrocytes. The ability of the modified IgG to bind to a DEAE-cellulose column was almost eliminated by reaction with the PEG 5000, and was decreased to a lesser extent by PEG 1900. This PEG 1900-modified IgG substantially increased the partition of fresh or fixed human erythrocytes into the PEG-rich phase of a suitable phase system, while having no effect on rabbit cell partition. The partition increase could be inhibited by unmodified anti-human red cell IgG but not by nonspecific unmodified human IgG, demonstrating that the ligand effects were specific for the cell type against which the antibody was raised. A mixture of rabbit and human erythrocytes, which ordinarily have very similar partitions in the phase systems used, could be separated on a countercurrent distribution apparatus using the modified IgG. These results demonstrate the feasibility of producing immunologically specific affinity partition ligands for cell separation.

Affinity Labels↗
PubMed1987

Improvement of the safety systems in cell separators. The new safety concept for the cell separator AS 104 (Fresenius).

The new, extended safety requirements for cell separators call for a new generation of machines to address current safety needs. In order to ensure safe treatment, the complete safety concept is of decisive importance - this includes closed seal-less systems, continuous operation, fractions collected externally to the centrifuge, and pump tubings, connections and clamps which are color and direction coded. 'Human failure' as a cause of fault should be excluded for these highly technical appliances - for example, through the use of 'fail-safe' circuits, drip-controlled ACD flow by a separate adjustable pump, detection of damages to blood components by hemolysis control.

Blood Component Removal↗
PubMed1976

Separation of tumor cells by density gradient centrifugation: recent work with human tumors and a discussion of the kind of quantitation needed in cell separation experiments.

The application of centrifugation to the purification of individual kinds of cells from tumors has been reviewed. Recent applications of a previously described isokinetic gradient to the purification of subpopulations of cells from human tumors are presented. Individual kinds of cells have been separated from Hodgkin's disease by a method described previously, and the cells from Hodgkin's disease which contain the tumor associated antigen described by Order and his colleagues have been identified for the first time. The importance of the thorough documentation of cell separation procedures is discussed, and we have specifically listed several kinds of data which we believe are important in the documentation of cell separation techniques.

Adenocarcinoma↗
PubMed1976

Lymphocyte activation by cell separation procedures.

Cell separation techniques normally used to obtain subpopulations of lymphocytes were shown, under certain conditions, to render the cells cytotoxic towards a number of target-cells including autologous lymphocytes. To cause cytotoxicity, it was necessary to pass cells through glass wool and/or nylon wool columns equilibrated with media containing fresh plasma or serum. Cells lost activation upon overnight in vitro culture or treatment with trypsin. In addition to direct cell cytotoxicity, cells released heat labile cytotoxic factors and antibody during the separation procedures. The implications of the results for the interpretation of cell separation studies designed to attribute immunological effects to one or another cell type were discussed.

Animals↗
PubMed1975

Free-flow electrophoresis. II. Analysis of the method with respect to preparative cell separation.

Electrophoretic cell separation by means of free-flow electrophoresis in an FF5 apparatus was investigated with respect to band resolution, separation capacity, reproducibility and influence on cell viability. Very sharp bands and a large separation capacity were achieved using triethanolamine/acetate buffered glycine media as liquid curtain. Acid buffer ions such as N-2-hydroxyethylpiperazine-N'-ethanesulfonic acid (HEPES) or phosphate produced broader bands. Osmotic expanders such as saccharides, though preserving cell viability excellently, decrease electrophoretic velocity and thus separation capacity. The decrease in cell viability observed in glycine media could be compensated for by addition of Ca2. Band broadening caused by methodologically specific velocity flow profiles could be reduced to a negligible level by coating the chamber walls with albumin and by appropriate adjustment of sample flow rate and liquid curtain velocity. Under the optimum conditions described, selective cell loss and artificial change in electrophoretic mobility of the cells during operation can be disregarded. The main reason for cell loss was cell aggregation at low ionic strength, which can be prevented or reversed by treatment of the cells with deoxyribonuclease.

Animals↗
PubMed1991

Effects of target antigen density on the efficacy of immunomagnetic cell separation.

Immunomagnetic cell separation uses binding of an antibody to its epitope to identify the target cell, which is then removed by attachment to an anti-immunoglobulin-coated paramagnetic bead, and passage through a magnetic field. This method has previously been shown to be less sensitive to the effects of low target antigen density than are other cell elimination methods, such as complement-mediated lysis. In this paper we demonstrate that, with certain antibody/target cell combinations, the efficiency of immunomagnetic depletion can be adversely affected by high expression of the target antigen. This can occur by two non-mutually exclusive mechanisms. These are (i) steric hindrance of bead binding due to crowding of monoclonal antibodies on the cell surface; and (ii) binding of the monoclonal antibody molecule in a configuration that is poorly-accessible to the anti-immunoglobulin immobilized on the microspheres. The predominant effect operating in any system can be determined by analysis of the cells remaining after the separation procedure. In both cases pre-attachment of the monoclonal to the beads results in improved separation efficiency. These results emphasize the necessity of optimizing experimental conditions in each system that is investigated.

Antibodies, Monoclonal↗
PubMed1975

Antigen-binding T cells as helper cells. Separation of helper cells by immune rosette formation.

The spleen T cells from mice immunized 6 days earlier with either chicken gamma globulin (CGG) or with donkey erythrocytes (DRC) were rosetted with CGG-coated sheep erythrocytes or with DRC. The immune rosettes (RFC) (antigen-binding cells) were separated from the bulk of nonrosette-forming cells (non-RFC) by 1-g velocity sedimentation and the RFC and non-RFC tested for helper activity in cooperative antihapten responses in vitro. RFC or non-RFC were mixed with normal or hapten-primed spleen cells, challenged with the appropriate hapten-carrier conjugate and cultured for 4 days in Marbrook tissue cultures. The helping activity was quantitated from the numbers of antihapten antibody-producing cells generated per culture. The results show that specific helper cell activity could be selectively recovered in the immune rosette-forming cell population whereas the non-RFC population was depleted of help. These findings indicate that the helper T cells express specific antigen binding receptors.

Animals↗