Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “LEUKOCYTES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed2005

Filter Buffy Coats (FBC): a source of peripheral blood leukocytes recovered from leukocyte depletion filters.

In compliance with federal regulations, blood banks routinely use leukocyte depletion filters to eliminate contaminating leukocytes from blood products such as red blood cell and platelet concentrates. We developed and optimized conditions to elute leukocytes adsorbed to these filters; resulting in leukocyte suspensions which we termed Filter Buffy Coats (FBCs). These Filter Buffy Coats can replace standard buffy coats for various research applications. After optimizing both the filter elution medium as well as elution protocols, we compared commonly used leukocyte depletion filters from four different manufacturers. Relative fractions as well as total recoveries of leukocyte subsets, such as lymphocytes, monocytes and granulocytes, found in Filter Buffy Coats were identified and compared among the filters as well as to standard buffy coats and whole blood. Flow cytometric analysis of Filter Buffy Coats confirmed the presence of T- and B-lymphocytes, NK cells and monocytes. Furthermore, a significant quantity of CD34(+) hematopoietic stem or progenitor cells (HSC/HPC) was detected in Filter Buffy Coats prepared from different filters, thus making FBCs a valuable source for research on HSC/HPC. Colony assays revealed that most of these CD34(+) cells are functional. Using immunomagnetic cell sorting (MACS), we isolated a variety of leukocyte populations from FBC mononuclear cells (Filter-PBMCs) including T lymphocytes (CD4(+), CD8(+), CD3(+)), B lymphocytes (CD19(+)), NK cells (CD56(+)), HSC/HPC (CD34(+), CD133(+)) or dendritic cells (BDCA-4(+)). Functional properties of Filter-PBMCs, as well as of some of these isolated leukocyte populations, were confirmed using standard assays. In summary, Filter Buffy Coats are a valuable and convenient source of different peripheral leukocyte populations and can replace standard buffy coat preparations for research applications.

Antigens, CD↗
PubMed2006

Leukocyte filtration to decrease the number of adherent leukocytes in the cerebral microcirculation after a period of deep hypothermic circulatory arrest.

OBJECTIVE: Cardiopulmonary bypass and hypothermic circulatory arrest induce a systemic inflammatory response, including a cascade of leukocyte and endothelial cell activity, during the postischemic reperfusion phase. Accumulation of leukocytes in the brain can lead to neurologic problems after cardiac surgery. The beneficial effects of a leukocyte-depleting filter have been documented, but because of contradictory results the underlying function of the filter remains unclear. METHODS: Twenty-two juvenile piglets (6 to 8 weeks) were randomly assigned to undergo cardiopulmonary bypass with or without a leukocyte-depleting filter 60 minutes before and 60 minutes after a 75-minute hypothermic circulatory arrest at 18 degrees C. The cerebral vessels were visualized with intravital microscopy through a cranial window placed over the parietal cortex. Rhodamine staining was used to observe adherent and rolling leukocytes in the cerebral postcapillary venules. The animals were electively killed 1 hour after weaning from cardiopulmonary bypass. RESULTS: There were no significant differences between the study groups regarding hemodynamic data. Numbers of adherent activated leukocytes were lower in the leukocyte filtration group, reaching borderline statistical significance when assessed throughout the experiment (between-groups P = .069) and actual statistical significance when assessed during the rewarming period (between-groups P = .029). CONCLUSION: The leukocyte-depleting filter succeeded in reducing the number of adherent leukocytes during the reperfusion period in an experimental operation with deep hypothermic circulatory arrest. Such a filter thus could mitigate cerebral reperfusion injury after cardiac surgery.

Animals↗
PubMed2001

Leukocyte activation and leukocyte procoagulant activities after blood contact with polystyrene and polyethylene glycol-immobilized polystyrene beads.

Beads (45 microm) of polystyrene (PS) and polyethylene glycol modified PS (TentaGel) with an amino or hydroxyl terminal group were incubated with blood to assess the effect of surface area and material chemistry on leukocyte activation. After a 2-hour incubation, blood contact with beads activated leukocytes in the bulk (tissue factor expression, CD11b up-regulation, and association with platelets) independently of material surface chemistry. On the other hand, activation of adherent leukocytes was material dependent. After blood contact with PS, polyethylene glycol-immobilized PS (PS-PEG) and PS-PEG-NH2 beads, CD11b up-regulation in the bulk, platelet-leukocyte aggregates, and leukocyte adhesion were all dependent on surface area, whereas tissue factor (TF) expression was not. Material-induced leukocyte activation in the bulk was also independent of the beads' capacity to activate platelets. However, monocyte adhesion and TF expression on beads appeared to be related to the presence of platelets on the surface. Material-induced TF expression was able to initiate the extrinsic pathway of coagulation, resulting in significant fibrin formation. Although not all of our markers of leukocyte activation varied with material area or chemistry, it was clear that these materials activated leukocytes in a way that resulted in increased procoagulant activity. During blood-material interactions, material-induced leukocyte activation may then contribute to thrombogenesis.

Blood Coagulation↗
PubMed1988

Preparation of leukocyte-poor platelet concentrates from buffy coats. III. Effect of leukocyte contamination on storage conditions.

To study the influence of contaminating leukocytes on the storage conditions of platelet concentrates (PC), various amounts of leukocytes were added to identical PC. From 12 blood donations, 12 leukocyte-poor PC were prepared and pooled. Subsequently, the pool was divided into 12 identical PC. The plasma volume of the PC was 58.6 +/- 0.6 ml, the platelet concentration was 1.01 +/- 0.04 x 10(9)/ml (mean +/- SD) and the red cell contamination did not exceed 10(7) per PC. To 4 groups of 3 PC, pooled leukocytes were added from the same 12 blood donations. The leukocyte contamination for each group of 3 PC was 0.14 +/- 0.05, 1.96 +/- 0.09, 5.53 +/- 0.98 and 13.0 +/- 0.93 x 10(6)/ml (mean +/- SD) for groups I-IV, respectively. The PC were stored for 7 days at 22 degrees C in normal polyvinylchloride bags. A significant correlation was found between increasing concentrations of leukocytes in the PC and the drop in pH (r = -0.93), glucose consumption (r = -0.91), lactic acid production (r = 0.93) and release of lactate dehydrogenase (r = 0.92) during storage of the PC. The excretion of beta-thromboglobulin, depletion of platelet adenine nucleotides, decreased ability to incorporate 3H-adenosine into metabolic nucleotides and poor morphology of the platelets were also significantly correlated with an increased number of leukocytes in the PC. These data show that high concentrations of leukocytes in PC have a significant detrimental effect on the viability of platelets during storage at 22 degrees C. We conclude that for good storage conditions of PC, the upper limit of leukocytes per PC should not exceed 10(7).

Blood Platelets↗
PubMed1976

Separation of mononuclear leukocytes and polymorphonuclear leukocytes from equine blood.

The present study describes a two step technique for the separation of mononuclear leukocytes or mononuclear and polymorphonuclear leukocytes from whole equine blood. First, the leukocyte rich plasma was obtained by sedimentation of erythrocytes in the undiluted blood. Subsequently, separation of the different populations of white blood cells was performed by centrifugation with different gradients overlaid with the leukocyte rich plasma. The optimal separation of the mononuclear cells was obtained by the centrifugation of the leukocyte rich plasma overlaying the gradient containing 24 parts of 9.5% ficoll and ten parts of 34% isopaque. The mononuclear leukocytes (95% lymphocytes and 5% monocytes) formed a monolayer band at the plasma-ficoll-isopaque interface and other blood cells migrated to the bottom of the tube. For the separation of mononuclear and granular leukocytes from the blood, the gradient containing 24 parts of 10% ficoll and ten parts of 34% isopaque was used. The separated monuclear leukocytes responded to stimulation with phytohemagglutin and viability of both mononuclear and polymorphonuclear leukocytes was not affected by ficoll-isopaque separation.

Animals↗
PubMed2001

Modulation of leukocyte-endothelium interaction by nitric oxide synthase inhibitors: effects on leukocyte adhesion in endotoxin-induced uveitis.

OBJECTIVE AND DESIGN: To examine the effects of the nitric oxide synthase (NOS) inhibitors aminoguanidine (AG) and L-NAME on leukocyte adhesion in endotoxin-induced uveitis (EIU). MATERIAL: Uveitis was induced in Lewis rats (n = 124) by LPS injection (Salmonella typhimurium). TREATMENT: Rats either (1) did not receive any LPS or other treatments (controls), received (2) only subcutaneous saline injections with LPS administration, (3) a single s.c. dose of AG (100 mg/kg body weight) at the time of LPS administration, (4) a single s.c. injection of AG 8 h after LPS injection, (5) s.c. injections of AG at the time of LPS administration and 8 h after LPS injection or (6) received a single dose of L-NAME (75 mg/kg body weight) at the time of LPS administration. METHODS: Intravital microscopy (IVM) of iris vessels was performed at 2, 4, 8, 16, 24 and 48 h after endotoxin injection. Aqueous humor analysis for protein concentration and cell count was performed after IVM. RESULTS: At 2 h after the induction of uveitis, significantly more rolling leukocytes were detected in the AG and L-NAME-treated group than in untreated EIU (4.8 +/- 0.31 and 9.83 +/- 0.64 vs. 2.85 +/- 0.37%, mean +/- SEM, p < 0.01). However, at 16 h the percentage of rolling leukocytes was significantly reduced in all groups which had received AG (LPS: 8.08 +/- 0.37%; LPS/AG 0 h: 3.78 +/- 0.25%; LPS/AG 8 h: 5.34 +/- 0.3%; LPS/AG 0+8h: 3.86 +/- 0.31%). L-NAME enhanced leukocyte rolling even at 24 h after LPS (12.38 +/- 0.64%). Early treatment of EIU with AG significantly reduced the number of sticking leukocytes at 4, 8 and 24 h (306 +/- 13 vs. 571 +/- 41, 228 +/- 12 vs. 345 +/- 19 and 240 +/- 14 vs. 469 +/- 23 cells/mm2, respectively). L-NAME inhibited LPS-induced sticking of leukocytes at all observed time points and this effect was most pronounced at 24 h (147 +/- 10 vs. 469 +/- 23 cells/mm2). CONCLUSIONS: In EIU, administration of AG or L-NAME causes enhanced leukocyte rolling in the early inflammatory response. However, firm adhesion of leukocytes to the vascular endothelium decreases and this effect prevails, ameliorating leukocyte infiltration.

Animals↗
PubMed1992

Effects of hydrodynamics and leukocyte-endothelium specificity on leukocyte-endothelium interactions.

In vivo microscopy was used to assess the relative contribution of hydrodynamic forces (network topography and shear rate) and the specificity for leukocytes to interact with venular endothelium as determinants of leukocyte-endothelium interactions. To ascertain this, microvascular networks in the rat and rabbit mesentery were examined under normograde and mechanically induced retrograde flows to determine the effect of reversed flow on leukocyte-endothelium interactions in arterioles and venules. The data indicate that retrograde perfusion under hemodynamic (red blood cell velocity and shear rate) states equivalent to normograde flow significantly increased leukocyte marginating flux in arterioles (from 0 to 0.5 cells/5 sec) and decreased flux significantly in venules (from 1.0 to 0.2 cells/5 sec). The increased flux in arterioles under retrograde conditions, however, was significantly lower than the flux in venules under normograde conditions and the decreased flux in venules during retrograde flow was significantly greater than the flux in arterioles during normograde flow. This apparent discrepancy appears to be the result of a heterogeneous distribution of adhesive receptors on vascular endothelium. Furthermore, marginating leukocytes in arterioles made only brief contact with the endothelium before being swept away while marginating leukocytes in venules during normal and retrograde perfusion rolled along the vascular wall, with similar velocities in both directions. In conclusion, although hydrodynamic forces are important in facilitating leukocyte margination through mechanisms of radial migration, it is leukocyte-endothelium specificity in venules that ultimately determines leukocyte-endothelium interactions.

Animals↗
PubMed1987

Amount and type of leukocytes in 'leukocyte-free' red cell and platelet concentrates.

The exact number of leukocytes remaining in 'leukocyte-free' red cell and platelet concentrates cannot be measured by standard methods. We have therefore developed methods to harvest all the leukocytes from blood components. The leukocytes were then counted and identified using monoclonal antibodies. The leukocyte-free red cell concentrates were prepared by combining buffy coat removal and filtration through a Cellselect filter. The mean number of leukocytes per unit was 1.0 X 10(5). Most of the leukocytes were granulocytes and T cells. Only a few B cells or monocytes could be detected. Leukocyte-free platelets were prepared by filtering 4 units of PC through a cotton-wool (Imugard) filter. The mean number of leukocytes per PC unit was 0.4 X 10(5) of which 85-95% were T cells.

Blood Cells↗
PubMed1985

Interleukin 1 acts on cultured human vascular endothelium to increase the adhesion of polymorphonuclear leukocytes, monocytes, and related leukocyte cell lines.

Increased leukocyte adhesion to the endothelial lining of blood vessels is an essential event in inflammation and the pathogenesis of certain vascular diseases. We have studied the effect of interleukin 1 (IL-1), an inflammatory/immune mediator, on endothelial-leukocyte adhesion using quantitative in vitro assays. Selective pretreatment of cultured human umbilical vein endothelial monolayers with IL-1 (5 U/ml, 4 h) resulted in an 18.3 +/- 2.6-fold increase in human peripheral blood polymorphonuclear leukocyte (PMN) adhesion (mean +/- SEM, n = 16) and a 2.6 +/- 0.3-fold increase in monocyte adhesion (n = 7) over basal levels. IL-1-treated endothelial monolayers also supported increased adhesion of the promyelocytic cell line HL-60 and the monocytelike cell line U937 (33.0 +/- 6.0-fold, n = 6 and 4.9 +/- 0.5-fold, n = 15, respectively). In contrast, selective IL-1 pretreatment of leukocytes, or the addition of IL-1 during the adhesion assay, did not alter endothelial-leukocyte adhesion. Conditioned medium from IL-1-treated endothelial cultures also did not promote leukocyte adhesion to untreated monolayers. IL-1 induction of endothelial adhesivity was concentration dependent (maximum, 10 U/ml), time dependent (peak, 4-6 h), and reversible, was blocked by cycloheximide (10 micrograms/ml) or actinomycin D (5 micrograms/ml) but not by acetylsalicylic acid (100 microM), and occurred without detectable endothelial cell damage. IL-1 treatment of SV40-transformed human endothelial cells and dermal fibroblasts did not increase their adhesivity for leukocytes. These data suggest that IL-1 can act selectively on human vascular endothelium to increase its adhesivity for circulating blood leukocytes, and thus to localize leukocyte-vessel wall interactions at sites of inflammation in vivo.

Cell Adhesion↗
PubMed1975

Determination of the glycogen content in single neutrophil leukocytes using a micromodel of leukocyte glycogen.

The kinetics of the periodic acid oxidation as part of the periodic acid-Schiff reaction was studied by combined microinterferometry and microspectrophotometry in micromodel systems of liver glycogen and leukocyte glycogen as well as in neutrophil leukocytes. The initial formation of Schiff-positive chromogens was more rapid in neutrophil leukocytes than in liver or leukocyte glycogen. The chromogen formation was, however, practically complete within 60 min in both neutrophil leukocytes and leukocyte glycogen, but this did not appear to be the case in liver glycogen. Differences in the rate of chromogen formation may depend on various factors such as differences in the source and treatment of the glycogen. The complete periodic acid-Schiff reaction appears to be a measure of the glycogen amount in neutrophil leukocytes and the microdroplet system of leukocyte glycogen is considered to be an appropriate model for the estimation of the glycogen amount in single neutrophil leukocytes. A mean value of 13.3 10-12 g glycogen per normal human neutrophil was found.

Glycogen↗
PubMed1991

Flavone acetic acid directly induces expression of cytokine genes in mouse splenic leukocytes but not in human peripheral blood leukocytes.

Flavone-8-acetic acid (FAA) is a flavonoid drug that augments mouse natural killer activity, induces cytokine gene expression, and synergizes with recombinant interleukin 2 for the treatment of murine renal cancer. However, FAA has been largely inactive in human clinical trials. In the present study we investigated the ability of FAA treatment to directly induce cytokine mRNA expression in total mouse splenic leukocytes and selected leukocyte subsets, as well as in total human peripheral blood leukocytes. Analysis of RNA isolated from FAA-treated mouse splenic leukocytes demonstrated that treatment with greater than or equal to 100 micrograms/ml of FAA induced expression of tumor necrosis factor alpha (TNF-alpha) mRNA by 1 h and induced maximal expression of TNF-alpha, alpha-interferon, and gamma-interferon mRNA within 3 h. The expression of all cytokine genes was diminished by 6 h. Interferon biological activity was detected in the supernatants of mouse splenic or peripheral blood leukocytes after treatment with FAA. These results correlate well with the previously reported induction of cytokine mRNA genes and biological activity by FAA in vivo. In contrast, FAA did not induce detectable mRNA expression or cytokine protein secretion by human peripheral blood leukocytes under similar conditions. These results demonstrate that FAA can directly stimulate cytokine gene expression in mouse but not in human leukocytes. Further studies performed with highly purified positively selected mouse CD4+ or CD8+ splenic T-lymphocytes, as well as purified B-cells, demonstrated that the FAA-induced expression of gamma-interferon mRNA was mainly induced in the CD8+ lymphocyte subset. alpha-Interferon mRNA was expressed largely in the B-cell population, while TNF-alpha mRNA was induced in all leukocyte subsets tested. Therefore, these results suggest that the immunomodulatory effects of FAA in mice are direct, but different cytokines are induced from different leukocyte subsets. Further, the data suggest that flavonoid compounds or analogues that stimulate cytokine gene expression in human cells might be therapeutically active in cancer patients.

Animals↗
PubMed1978

Amplification of the activity of human leukocyte inhibitory factor (LIF) by the generation of a low molecular weight inhibitor of PMN leukocyte chemotaxis.

Leukocyte inhibitory factor (LIF), which was derived from human peripheral blood lymphocytes by stimulation with concanavalin A ad partially purified by Sephadex G-100 gel filtration, inhibited the in vitro spontaneous migration and chemotaxis of human PMN leukocytes as assessed in a Boyden chamber micropore filter assay. The inhibitory activity was attributed to LIF, a principle defined in terms of its inhibition of PMN leukocyte migration from glass capillary tubes since it was preferentially directed to PMN leukocytes as compared to mononuclear leukocytes, exhibited a size comparable to LIF by gel filtration, and was inactivated by diisopropyl fluorophosphate in parallel with LIF. Incubation of PMN leukocytes with LIF released additional inhibitory activity, distinct from LIF, which resembled the neutrophil-immobilizing factor (NIF) by virtue of its approximate m.w. of 4000 by filtration on Sephadex G-25, inactivation by trypsin digestion, and preferential noncytotoxic inhibition of spontaneous migration and chemotaxis of PMN leukocytes as compared to mononuclear leukocytes. Thus LIF inhibits PMN leukocyte migration both by a direct action on the cells and by an amplification pathway that is mediated by low m.w. chemotactic inhibitors similar to NIF.

Chemotaxis, Leukocyte↗