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.

SourceResearch connectionFrom yearThrough year

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

At least 163 records · Page 9Linked to original sources

PubMed1990

The role of graft-derived dendritic leukocytes in the rejection of vascularized organ allografts. Recent findings on the migration and function of dendritic leukocytes after transplantation.

Dendritic cells isolated from lymphoid tissues are potent stimulators of primary allogeneic T-cell responses in vitro and in vivo. Similar major histocompatibility complex class II-bearing dendritic-shaped leukocytes are contained within transplanted organs and these are thought to be important passenger leukocytes that trigger rejection. Recent findings on the migration, phenotype, and function of cardiac dendritic leukocytes (DLs) are reviewed. After transplantation donor DLs migrate rapidly from mouse cardiac allografts into the recipients's spleens. Within the spleens donor DLs associate with recipient CD4+ T cells. Isolated cardiac DLs, like lymphoid dendritic cells, are potent stimulators of T-cell proliferation in vitro. This suggests that DLs function as passenger leukocytes by migrating from grafts into the lymphoid tissues of the recipient and that sensitization to vascularized organ allografts may occur centrally within lymphoid tissues rather than peripherally in the graft itself.

Animals↗

PubMed1997

Leukocyte adhesion--structure and function of human leukocyte beta2-integrins and their cellular ligands.

Leukocyte adhesion is of pivotal functional importance and this has resulted in extensive research and rapid development in the field. Leukocyte adhesion involves members of three molecular families: integrins, members of the immunoglobulin superfamily and carbohydrate binding selectins and sialoadhesins. Recently, considerable structural information on leukocyte integrins and members of the immunoglobulin superfamily of adhesion molecules has been obtained. This fact, combined with the identification of several novel adhesion molecules, has increased our understanding of how they function at the molecular level. Furthermore, the important issue of how integrins are activated to become adhesive is rapidly advancing. It is clearly evident that the knowledge accumulated from basic research will increasingly be applied in clinical medicine. In this review we focus on two important families of adhesion molecules, the leukocyte-specific beta2-integrins and their ligands, the intercellular adhesion molecules. Emphasis is put on their structural/functional relationships, their mode of regulation and on novel adhesion molecules recently discovered.

Amino Acid Sequence↗

PubMed1985

Evaluation of cellular immune response during chronic schistosomiasis in humans by the leukocyte aggregation test and the leukocyte migration inhibition test.

Cellular immune response was evaluated in 31 patients with chronic Schistosoma haematobium and Schistosoma mansoni infections and in 15 healthy normal persons by using S. mansoni soluble worm and egg antigens. Although the leukocyte migration inhibition test demonstrated false-positive reactions, the specificity of the leukocyte aggregation test was confirmed by the negativity of all of the controls. Among the patients, only 10% were positive for the leukocyte aggregation test. This low cellular reactivity was in contrast to markedly elevated specific humoral response determined by an enzyme-linked immunosorbent assay for immunoglobulin G and paper allergosorbent test for immunoglobulin E with soluble worm antigen. These results confirm that the cellular immune reactivity to schistosome antigen as demonstrated by the leukocyte aggregation test is either minimal or absent in chronically infected patients.

Antigens, Helminth↗

PubMed1993

Measles virus-induced changes in leukocyte function antigen 1 expression and leukocyte aggregation: possible role in measles virus pathogenesis.

Measles virus (MV) infection of U937 cell or peripheral blood leukocyte cultures was shown to induce changes in the expression of leukocyte function antigen 1 (LFA-1) and cause marked aggregation of these cells. Addition of selected monoclonal antibodies specific for LFA-1 epitopes that did not neutralize MV in standard neutralization assays were found to block both virus-induced leukocyte aggregation and virus dissemination. These data suggest that MV modulation of LFA-1 expression on leukocytes may be an important step in MV pathogenesis.

Antibodies, Monoclonal↗

PubMed2000

Improved sensitivity in the measurement of residual leukocytes in platelet products using an automated leukocyte counter.

BACKGROUND AND OBJECTIVES: Leukocytes remaining in platelet concentrates may be responsible for side effects caused by platelet transfusion. A simple method of high sensitivity for determining trace numbers of leukocytes is currently needed. MATERIALS AND METHODS: An automated leukocyte counter, the LD-1000, the principle of which is a combination of spinning down on the observation field of stained nuclei derived from a 100 microl neat sample and image digitization with a charge coupled device camera, was newly developed and tested for sensitivity and reproducibility. RESULTS: While the theoretical lower limit of detection was 0.01 cells/microl, the limit of detection of the LD-1000 was verified to be 0.2 cells/microl. A good correlation (r = 0.86) was observed between the results obtained using the Nageotte method and the LD-1000. Repeated measurements also confirmed satisfactory reproducibility. CONCLUSIONS: The instrument provides a new method of enumerating residual leukocytes in platelet products with better sensitivity and easier procedure compared to the Nageotte method and will be useful for quality assurance purposes at blood centers.

Humans↗

PubMed1989

Alterations in function and subpopulations of peripheral blood mononuclear leukocytes in children with portal hypertension. Leukocyte subtypes and function in portal hypertension.

Children with advanced portal hypertension usually have splenomegaly (often associated with hypersplenism) which may lead to a decreased life span of circulating blood leukocytes. In a group of 6 children (age range 4-15 years; mean age 8.5 years) with portal hypertension, we examined peripheral blood mononuclear leukocytes for possible changes in their proportions, numbers and function. Compared to normal subjects, children with portal hypertension had a marked reduction in the percentages and absolute numbers of T lymphocytes (CD3+), T 'helper/inducer' (CD4+) and T 'suppressor/cytotoxic' (CD8+) cells. However, the percentages of B lymphocytes (FMC1+), natural killer cells (Leu 11+) and monocytes (morphological) were increased, and the absolute numbers of B cells were significantly increased in these patients. Lymphocyte responsiveness to phytohemagglutinin, pokeweed mitogen and concanavalin A were depressed in the patients, while the natural killer cell cytotoxicity was slightly increased. Thus, children with portal hypertension show changes in the relative proportions and absolute numbers of peripheral blood mononuclear blood leukocyte subpopulations as well as changes in mononuclear leukocyte function.

Adolescent↗

PubMed1992

The effects of pulsatile flow on the leukocyte depleting qualities of the Pall LG6 leukocyte depleting arterial line filter: a laboratory investigation.

The Pall LG6 arterial line filter has, in a previous publication, demonstrated its inherent leukocyte depleting qualities. This initial study was however carried out under continuous flow conditions. The present study was designed to assess the effectiveness of the LG6 filter in performing this leukocyte removal function under the more dynamic conditions of pulsatile flow. In addition to leukocyte depletion, the general blood handling and degree of energy absorption associated with the LG6 and Stat-Prime filters was also assessed. The results demonstrated that the LG6 filter was unaffected by the flow regime employed in terms of leukocyte removal and platelet depletion. There was a higher level of measured haemolysis associated with the use of pulsatile rather than nonpulsatile flow, however, this was the case with both filter types and was not found to be the case when generated values were computed. The LG6 filter absorbed more energy than the Stat-Prime filter as reflected by energy equivalent pressure (EEP) measurement, but this difference did not reach a level which was considered to be clinically significant.

Animals↗

PubMed2004

Leukocyte-derived myeloperoxidase amplifies high-glucose--induced endothelial dysfunction through interaction with high-glucose--stimulated, vascular non--leukocyte-derived reactive oxygen species.

Vascular non-leukocyte-derived reactive oxygen species (ROS), such as superoxide and hydrogen peroxide (H(2)O(2)), have emerged as important molecules in diabetic endothelial dysfunction. In addition, leukocyte-derived myeloperoxidase (MPO) has been implicated in vascular injury, and its injury response is H(2)O(2) dependent. It is well known that MPO can use leukocyte-derived H(2)O(2); however, it is unknown whether the vascular-bound MPO can use high-glucose-stimulated, vascular non-leukocyte-derived H(2)O(2) to induce diabetic endothelial dysfunction. In the present study, we demonstrated that MPO activity is increased in vessels from diabetic rats. In high-glucose-incubated rat aortas and in carotid arteries from rats with acute hyperglycemia, vascular-bound MPO utilized high-glucose-stimulated H(2)O(2) to amplify the ROS-induced impairment of endothelium-dependent relaxation via reduction of nitric oxide bioavailability. Hypochlorous acid (HOCL)-modified LDL, a specific biomarker for the MPO/HOCL/chlorinating species pathway, was detected in LDL- and MPO-bound vessels with high-glucose-stimulated H(2)O(2). The results suggest that vascular-bound MPO could use high-glucose-stimulated H(2)O(2) to amplify high-glucose-induced injury in the vascular wall. MPO/H(2)O(2)/HOCL/chlorinating species may represent an important pathway in diabetes complications and a new mechanism in phagocyte- and systemic infection-induced exacerbation of diabetic vascular diseases.

Animals↗

PubMed1996

Role of leukocytes and leukocyte adhesion molecules in renal ischemic-reperfusion injury.

Renal ischemic-reperfusion injury (IRI) occurs frequently in transplanted as well as native kidneys. Effective treatment for this process is still elusive. Leukocytes and their products may be important in the pathogenesis of renal IRI, however their role is still controversial. Recently, adhesion receptors on leukocytes and their corresponding ligands have been identified. In the heart, considerable evidence supports the role of CD11/CD18, ICAM-1, and the selectin receptors in IRI. However, based on experimental studies in animal models, even though renal IRI appears to be ICAM-1 mediated, the role of the CD11/CD18 pathway appears to be minimal. In addition, the available evidence does not support the concept that L-selectin has significant involvement in renal IRI. In this review, the data and controversies regarding the role of leukocytes and leukocyte adhesion molecules in renal IRI are discussed.

Animals↗

PubMed1999

Leukocyte adhesion molecules and leukocyte-platelet interactions during hemodialysis: effects of different synthetic membranes.

Membranes made from synthetic polymers, in general, are considered as being biocompatible membranes and tend to be treated as a homogeneous group. However, all of these membranes have multiple and different characteristics that may contribute to interactions with blood components. As a consequence, the biocompatibility profile of synthetic membranes may vary. In the present cross-over study, we examined by flow cytometry the effects (expressed as % change from predialysis values) of three different synthetic polymers (polysulfone, PSF; polyacrylonitrile-co-sodium methallyl sulfonate, AN69; ethylenevinylalcohol, EVAL) on the expression of leukocyte adhesion molecules (CD11b/CD18, CD15s) and the interactions between leukocytes and platelets under conditions of routine clinical use. For neutrophils, a statistically significant difference was found in CD15s expression for EVAL as compared to AN69 (p<0.05) and in CD11b/CD18 expression for PSF as compared to both EVAL (p<0.01) and AN69 (p<0.05). No difference between membranes was found on the expression of such adhesive molecules on monocytes. Significant differences in platelet-neutrophil (but not in platelet-monocyte) coaggregate formation were observed between PSF and both EVAL (p<0.001) and AN69 (p<0.01). Reactive oxygen species production by neutrophil population during hemodialysis was significantly different between each pair of synthetic polymers (PSF vs EVAL, p<0.001; PSF vs AN69, p<0.001; AN69 vs EVAL, p<0.05). Our data demonstrate that in terms of leukocyte adhesion receptors and platelet-leukocyte interactions, the biocompatibility profile of the synthetic membranes polysulphone, AN69 and EVAL shows many similarities but also several significant differences. Our results support the concept that biocompatibility evaluation of each membrane should be based exclusively on data generated by that membrane in order to avoid errors based on assumptions about group characteristics.

Acrylic Resins↗

PubMed1992

Estimated synovial fluid leukocyte numbers on wet drop preparations as a potential substitute for actual leukocyte counts.

Leukocyte counts on synovial fluid are widely used in classification of joint disease as inflammatory or "noninflammatory." We have evaluated estimates of leukocytes (WBC) per high power field (HPF) on wet drop preparations to see if they might be suitable substitutes in some situations. If there was a mean WBC of 0-2/field on 10 HPF, all leukocyte counts were less than 1,300/mm3. Thus, in such fluids expense might be reduced by eliminating the actual leukocyte count. Estimates also roughly correlated with WBC counts at higher counts but were less consistent.

Arthritis↗

PubMed2005

Clopidogrel inhibits platelet-leukocyte adhesion and platelet-dependent leukocyte activation.

Clopidogrel is considered to be an important therapeutic advance in anti-platelet therapy. We investigated whether inhibition by clopidogrel results in a reduced capacity of platelets to adhere and stimulate pro-atherothrombotic and inflammatory functions in polymorphonuclear leukocytes (PMN) and in monocytes (MN). An eventual effect on these processes could further substantiate anti-atherothrombotic properties of this drug. The effects of clopidogrel or of its active metabolite were investigated on ADP or thrombin receptor-induced platelet activation and on platelet-leukocyte interactions ex vivo in the mouse or in vitro in isolated human cells or whole blood, respectively. Clopidogrel inhibited platelet aggregation, expression of P-selectin, platelet-PMN adhesion and platelet-dependent ROS production in mouse PMN. Similarly pretreatment of human platelets with the active metabolite of clopidogrel in vitro resulted in a profound inhibition of platelet P-selectin expression, platelet-PMN adhesion and production of ROS by PMN. Pretreatment with the active metabolite of clopidogrel significantly impaired the ability of platelets to up-regulate the expression of TF procoagulant activity in MN, in a washed cell system. Moreover, the active metabolite of clopidogrel inhibited rapidTF exposure on platelet as well as on leukocyte surfaces in whole blood. By reducing platelet-dependent up-regulation of inflammatory and pro-atherothrombotic functions in leukocytes, clopidogrel may reduce inflammation that underlies the chronic process of atherosclerosis and its acute complications.

Animals↗

PubMed1989

Leukocyte deformability--a comparison between different methods for separation of rat leukocytes from whole blood.

The deformability of rat leukocytes isolated by three different methods (Ficoll-Sodium Metrizoate, Ficoll-Hexabrix and Percoll) was studied with micropipette technique. The internal diameter of the micropipette tip was 4.0 microns and a constant aspiration pressure of -15 cm H2O was suddenly applied. The time course of deformation of the cells was analysed with video technique. The rat leukocytes showed the same viscoelastic deformation pattern as has been described earlier for human leukocytes. There was no significant difference in deformability between the three different lymphocyte (LC) fractions or between the two different polymorphonuclear granulocyte (PMN) fractions that were studied. The initial, rapid phase deformation was similar for LCs and PMNs, whereas the PMNs showed a considerably slower second phase deformation. This difference between LCs and PMNs is probably due to the larger size of the PMNs and the larger adhesive shear stresses acting on these cells. It is concluded that the three methods used for separation of rat leukocytes are equivalent in respect to the deformability of the cells produced.

Animals↗

PubMed1987

Transformation of human leukocytes by co-cultivation with HTLV-1-associated myelopathy patients' leukocytes.

Sera and cerebrospinal fluid (CSF) from patients with human T-cell leukemia virus type 1 (HTLV-1)-associated myelopathy (HAM) were analyzed by Western blotting, and normal human leukocytes were transformed by co-cultivation with HAM patients' leukocytes. The sera and CSF from all HAM patients formed specific bands with HTLV-1 viral proteins, including p19, p24, p28, p32, p40 and p53. After 2-3 weeks of co-cultivation, scattered foci of cell aggregates were noted on macrophage sheets. Surface markers of the transformed cells were OKT3(+), OKT4(+), OKT8(-), IL-2 receptor(+) and EBNA(-). Chromosome analysis showed a normal karyotype. HTLV-1 viral genome was integrated into DNA isolated from transformed cell lines. Electron microscopy revealed type C virus particles in transformed T-cell lines. These results indicate that peripheral leukocytes from HAM patients can transform HTLV-1-negative leukocytes and HAM patients have the potential to acquire adult T-cell leukemia in the future.

Adult↗

PubMed1985

Isolation and characterization of porcine leukocyte elastase. Leukocyte elastase-inhibitor complexes in porcine blood, II.

Porcine leukocyte elastase was purified from granulocytes by chelating chromatography on copper chelate Sepharose and by ion exchange chromatography on CM-Sepharose. Thus an enzyme preparation with a specific activity (substrate: MeOSuc(Ala)2ProValNan) of 89.3 U/mg protein was obtained. Dodecyl sulphate gel electrophoresis revealed one protein band corresponding to a molecular mass of 27 kDa. The amino acid composition was determined and isoleucine was identified as the only N-terminal amino acid residue. The bimolecular velocity constant for the inhibition by diisopropyl fluorophosphate was determined as 2000 1 . mol-1 . min-1. The dissociation constants, Ki, of the complexes of porcine leukocyte elastase with various inhibitors were calculated. The kinetic constants for the elastase-catalysed hydrolysis of MeOSuc(Ala)2ProValNan, Suc(Ala)2ValNan and Suc(Ala)3Nan were determined, as well as the kinetic constants of the inactivation of leukocyte elastase by active site mapping reagents. Detergents such as Triton X-100, Tween 20 and Brij 35, as well as porcine serum albumin, activated the porcine leukocyte elastase preparation.

Animals↗

PubMed1983

Actin changes in normal human and rat leukocytes and in transformed human leukocytic cells.

The DNase I inhibition assay was used for the determination of the relative amounts of monomeric and total actin in normal human peripheral blood lymphocytes, normal Sprague-Dawley rat peritoneal leukocytes, and 6 transformed human cell lines of lymphoid and myeloid origins. In the normal lymphocytes and leukocytes, greater than 50% of the total actin was monomeric. In contrast, only 1 of the 6 transformed lines had greater than 50% of its actin in the monomeric form. In the other 5 lines, the percentage of actin in the monomeric form ranged from 23 to 39%. The normal lymphocytes, peritoneal leukocytes, and 2 of the transformed cell lines (CEM and K562) were examined in greater detail. The total actin (as a percentage of the total protein) was found to be much lower in the transformed cell lines than it was in the normal lymphocytes. The total amount of actin in the normal rat leukocytes was very similar to the amount in the normal human lymphocytes. In addition to these differences between the normal and transformed human cells, treatment of the normal lymphocytes with mitogenic doses of concanavalin A was found to significantly reduce the amount of monomeric actin in the cells. Similar treatment of the transformed cells produced no significant reduction in the monomeric actin.

Actins↗

PubMed1981

Stimulation of the elastolytic activity of leukocyte elastase by leukocyte cathepsin G.

Human leukocyte cathespin G strongly stimulates the rate of solubilization of human lung elastin by human leukocyte elastase. For instance, the elastolytic activity of an equimolar mixture of elastase and cathepsin G is more than 5 times higher than that of elastase alone. Optimal stimulation occurs only if cathepsin G and elastase act simultaneously on elastin. Potentiation of leukocyte elastase digestion of lung elastin may also be brought about by bovine alpha-chymotrypsin. This enzyme is about half as efficient as cathepsin G. Stimulation of leukocyte elastase activity by cathepsin G is about 3 times less pronounced with bovine ligamentum nuchae elastin than with human lung elastin. On the other hand, the elastolytic activity of porcine pancreatic elastase is only enhanced by 20 to 30% by cathepsin. Therefore, maximal potentiation of elastolysis occurs with the lung elastin/leukocyte elastase system. The pathologic relevance of these findings is discussed.

Amino Acids↗

PubMed1982

Correlation of leukocyte esterase detection and the presence of leukocytes in body fluids.

The Chemstrip-L test was evaluated in 249 body fluids for its ability to detect leukocytes. Three of 42 cerebrospinal fluids were positive for leukocyte esterases, of which all three were cases of culture-confirmed bacterial meningitis. After the addition of predetermined numbers of neutrophils, the lowest level of detection of neutrophils in cerebrospinal fluids was 40 per microliter. Seventy-five of 200 (38%) peritoneal fluids had positive leukocyte esterase tests. Sixty-six of 72 (89%) peritoneal fluids with 100 or greater neutrophils per microliter had positive leukocyte esterase tests. Protein content, if increased, may interfere with the results of the L-test.

Ascitic Fluid↗