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Query: UMLS:C0027947 (neutropenia)
 17,527 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Infusion of activated plasma induces neutropenia and sequestration of neutrophils within the microvasculature. This study examined the role of the adhesion glycoprotein complex, CD11/CD18, in this sequestration. Rabbits pretreated with either the anti-CD18 monoclonal antibody (mAb) 60.3 or saline were given infusions of zymosan-activated plasma (ZAP) or saline. The effect of mAb 60.3 on the changes in circulating neutrophil counts, radiolabeled neutrophil kinetics in the lung, and the pulmonary microvascular accumulation of neutrophils induced by ZAP infusion was determined. The data show that pretreatment with mAb 60.3 did not inhibit either the rate of onset or the severity of the neutropenia but prevented the sustained neutropenia. In addition, mAb 60.3 completely prevented the ZAP-induced changes in radiolabeled neutrophil kinetics and largely inhibited the accumulation of neutrophils within the capillaries and the small vessels when evaluated after 15 min of ZAP infusion. We conclude that neutrophil accumulation is a two-step process, the first occurring through a CD18-independent mechanism that may involve a stimulus-induced decrease in neutrophil deformability and acts to slow neutrophil transit through the lung. The second step requires CD18-dependent adhesion and is needed for prolonged accumulation of neutrophils within the pulmonary microvasculature.
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PMID:The role of CD18-mediated adhesion in neutrophil sequestration induced by infusion of activated plasma in rabbits. 135 74

Hemodialysis with first-use cellulosic dialysis membranes results in activation of the alternative pathway of complement and profound neutropenia followed by rebound leukocytosis. The neutropenia has been shown to be associated with increased expression of adhesion receptors and pulmonary sequestration of granulocytes. However, the mechanism underlying the return of the granulocytes has not been elucidated. We determined simultaneously the changes in the granulocyte adhesion receptor MAC-1 (CD11b-CD18) and the selectin LAM-1 receptor during dialysis using a complement activating and a non-complement activating membrane, in a randomized, cross-over study. With initiation of dialysis with cellulosic membranes, there was a rapid and prominent increase in the expression of MAC-1 receptors. At the nadir of granulocyte count, 15 minutes after initiation of dialysis with the complement activating membrane, there was a four-fold increase in the MAC-1 receptor expression. At the same time, there was a two-fold decrease in LAM-1 expression. There were no changes in the expression of two other granulocyte receptors CD11a and CD15 which are known not to be modulated during granulocyte activation. Granulocytes harvested during dialysis and which had high MAC-1 and low LAM-1 expression had a significantly decreased adherence to endothelial cell monolayers. Dialysis of the same patients with non-complement activating membranes resulted in no significant change in the expression of these receptors on granulocytes nor in their adherence to endothelial cells. These results shed new light on the mechanism of the cyclical granulocytopenia and rebound granulocytosis during dialysis with new cellulosic membranes.
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PMID:Modulation of granulocyte LAM-1 and MAC-1 during dialysis--a prospective, randomized controlled trial. 137 68

To determine the mechanisms whereby complement-activated granulocytes induce microvascular dysfunction in skeletal muscle, we examined the effect of antineutrophil serum (ANS), IB4 (a monoclonal antibody that inhibits CD18-dependent neutrophil adherence), xanthine oxidase inhibition or inactivation, deferoxamine, and catalase on the increase in canine gracilis muscle microvascular permeability induced by intravascular administration of zymosan-activated plasma (ZAP). Changes in vascular permeability were assessed by measurement of the solvent drag reflection coefficient (sigma) for total plasma proteins, and the extent of neutrophil infiltration was estimated by assessing muscle myeloperoxidase activity. ZAP infusion was associated with a marked increase in vascular permeability compared with control muscles that received no treatment or to muscles treated with zymosan heat-inactivated plasma (ZIP) (sigma = 0.51 +/- 0.04, 0.89 +/- 0.02, and 0.90 +/- 0.01, respectively). Estimates of sigma in animals rendered neutropenic with ANS, or treated with IB4, deferoxamine, or catalase before ZAP infusion were not significantly different from values obtained in control or ZIP-treated muscles (sigma = 0.96 +/- 0.02, 0.88 +/- 0.03, 0.85 +/- 0.02, and 0.79 +/- 0.01, respectively). However, xanthine oxidase inactivation or inhibition provided no protection from this ZAP-induced microvascular dysfunction (sigma = 0.58 +/- 0.02 and 0.58 +/- 0.01, respectively). In addition, neutropenia and inhibition of neutrophil adherence also prevented ZAP-induced increases in vascular resistance and tissue neutrophil infiltration.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Oxidant-mediated, CD18-dependent microvascular dysfunction induced by complement-activated granulocytes. 167 94

Sequestration of neutrophils (PMNs) in the pulmonary microvasculature and associated neutropenia are characteristic features of experimental models of septic lung injury. The etiology of altered PMN kinetics during septic lung injury is uncertain, but may be partially due to increased adhesiveness of activated PMNs to pulmonary endothelium. This study examines the relationship between the expression of PMN CD18 adhesion receptors, the evolving neutropenia, and plasma tumor necrosis factor (TNF) activity in a porcine model of septic lung injury. Acute lung injury was induced by infusion of live Pseudomonas aeruginosa (5 x 10(8) CFU/ml at 0.3 ml/20 kg/min) for 60 min (Group Ps, n = 6). Control animals (Group C, n = 3) received a 60-min infusion of sterile 0.9% saline. CD18 expression of circulating PMNs was measured by quantitative immunofluorescent flow cytometry. Plasma TNF activity was measured by L929 fibroblast cytolytic assay. Group Ps developed a significant neutropenia by 30 min (14.9 +/- 2.5 vs 23.4 +/- 3.3 x 10(3) cells/microliter at baseline, P less than 0.05, ANOVA) with circulating neutrophils exhibiting significantly increased CD18 expression by 60 min (6.34 +/- 0.72 vs 5.01 +/- 0.52 equivalent soluble fluorescence molecules (ESFM) x 10(3) at baseline, P less than 0.05, ANOVA). Group Ps demonstrated a significant increase in plasma TNF activity by 30 min (2.5 +/- 0.9 vs 0.7 +/- 0.3 U/ml at baseline). There was no significant change in PMN count, PMN CD18 expression, or plasma TNF activity in Group C. In complimentary in vitro studies, porcine PMNs stimulated with recombinant human TNF-alpha (n = 5) demonstrated a time- and dose-dependent increase in CD18 expression.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:CD18 adhesion receptors, tumor necrosis factor, and neutropenia during septic lung injury. 167 83

Activated polymorphonuclear leukocytes (PMNs) are implicated in the pathogenesis of acute lung injury (ALI) associated with sepsis. Adhesion of activated PMNs to endothelial monolayers is mediated by the CD18 adhesion-receptor complex on the PMN cell surface. Monoclonal antibody 60.3 (MoAb 60.3) blocks CD18-dependent PMN-endothelial adhesion in vitro and in vivo. This study was designed to determine the role of CD18-dependent PMN adhesion in ALI associated with gram-negative sepsis. Anesthetized, ventilated (FiO2 0.5, positive end-expiratory pressure 5 cm H2O) pigs received sterile saline (control, n = 8) or live Pseudomonas aeruginosa, 5 x 10(8) colony-forming units/ml at 0.3 ml/20 kg/min (septic, n = 9) for 1 hour. A third group (n = 7) received MoAb 60.3, 2 mg/kg intravenously, 15 minutes before Pseudomonas infusion. Animals were studied for 300 minutes. MoAb 60.3 significantly (p less than 0.05) attenuated the neutropenia seen in sepsis (15 +/- 1 vs 6 +/- 1 x 10(3) PMNs/mm3 at 300 min). Alveolar-capillary membrane injury was assessed by bronchoalveolar-lavage protein content and extravascular lung water determination. MoAb 60.3 significantly (p less than 0.05) reduced BAL protein at 300 minutes (388 +/- 75 vs 1059 +/- 216 micrograms/ml in septic animals) and attenuated the increase in extravascular lung water to 240 minutes (7.1 +/- 2 vs 14.2 +/- 1.2 ml/kg in septic animals). Systemic hypotension, decreased cardiac index, pulmonary hypertension, and relative hypoxemia, all characteristic of this model, were not altered by MoAb 60.3. These data suggest that, in this model of septic ALI, neutropenia is, in part, CD18 dependent and that blocking CD18-dependent PMN adhesion protects the alveolar-capillary membrane independently of altered hemodynamic status.
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PMID:Anti-CD18 antibody attenuates neutropenia and alveolar capillary-membrane injury during gram-negative sepsis. 167 91

Anti-neutrophil antibodies have been described in a variety of clinical conditions associated with neutropenia. However, relatively little is known about the antigenic specificities of naturally occurring anti-neutrophil autoantibodies. We investigated the possibility that anti-neutrophil antibodies specific for the neutrophil adhesion glycoprotein (GP) complex CD11b/CD18 might be present in the sera of some patients with autoimmune neutropenia. These membrane GPs have been shown to be highly immunogenic in the production of murine monoclonal antibodies against neutrophil antigens. Moreover, autoantibodies to the platelet membrane GP complex IIb/IIIa, another member of the integrin family of cell adhesion proteins, have been demonstrated in immune thrombocytopenic purpura. Sera from 50 patients known to have anti-neutrophil IgG antibodies were evaluated using an immunobead "antigen capture" assay, modeled after a method used to identify anti-platelet GPIIb/IIIa autoantibodies. This assay detected anti-CD11b/CD18 autoantibodies in seven of the 50 sera. Each of these seven sera demonstrated decreased IgG binding to the neutrophils of a patient with congenital deficiency of CD11b/CD18. The patient with the highest levels of anti-CD11b/CD18 suffered recurrent skin infections and cellulitis, and died of respiratory failure during one of multiple episodes of pneumonia. Purified IgGs from five of these patients demonstrated effects on adhesion and/or opsonin receptor-mediated functions when tested with intact neutrophils in vitro. Our findings indicate that some patients with autoimmune neutropenia have autoantibodies specific for the functionally important neutrophil adhesion proteins CD11b/CD18. Our findings also raise the possibility that these autoantibodies may, in some cases, interfere with neutrophil function, thereby amplifying the risk of infection associated with neutropenia.
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PMID:Identification of autoantibodies specific for the neutrophil adhesion glycoproteins CD11b/CD18 in patients with autoimmune neutropenia. 167 88

To elucidate the molecular mechanisms accounting for hemodialysis-induced neutropenia, the regulation of plasma membrane expression of leukocyte adhesion glycoproteins was investigated by both flow cytometry and immunoprecipitation techniques. The members of the LFA family of integrins, Mac-1/Mo1 (CD11/CD18) and gp150/95 (CD11c/CD18), involved in adhesion of myeloid cells to endothelia and other substrates, were found to be overexpressed on the plasma membrane of neutrophils from patients undergoing hemodialysis with a Cuprophane dialyzer, whereas no change was observed in the expression of LFA-1 (CD11a/CD18). By contrast, dialysis with Cuprophane membranes, as well as in vitro treatment with different activating agents, induced a downregulation on the expression of both the Leu-8/LAM-1 antigen, the human neutrophil peripheral lymph node homing receptor, and the CD43 major sialoglycoprotein involved in leukocyte homotypic adhesion. Kinetics studies showed that these up- and downregulatory processes of antigen expression occur very rapidly, correlating with maximal neutropenia. Recovery of initial levels of expression of CD11b/CD18 and Leu-8/LAM-1 adhesion molecules was observed after one hour of hemodialysis. However, the basal expression of CD43 was not restored by that time. The coordinated upregulation of CD11b and CD11c and downregulation of LAM-1 and CD43 adhesion receptors provide molecular mechanisms for understanding leukoaggregation, adherence to endothelia, and extravasation of neutrophils ultimately leading to the hemodialysis-induced neutropenia.
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PMID:Differentially regulated cell surface expression of leukocyte adhesion receptors on neutrophils. 176 94

Adherence of leukocytes to the endothelium is a prerequisite for infiltration and accumulation of cells at an inflammatory site. Recent studies suggest that the CD11/CD18 family of adhesion-promoting receptors plays a crucial role in the initial adherence of polymorphonuclear leukocytes (PMNs) to endothelium. We have studied the effect of the anti-CD18 monoclonal antibody (MoAb) IB4, on movement of PMN in rabbits. Accumulation of PMNs in the skin induced by a local injection of the chemoattractant, zymosan-activated serum (ZAS), was strongly inhibited, in a dose-dependent fashion, by intravenous injection of IB4. A greater than 95% reduction in PMN accumulation was seen with 1 mg IB4/kg body weight, the highest dose used. PMN-dependent plasma leakage in the ZAS-injected skin sites was also inhibited by pretreatment with MoAb IB4, with a similar dose dependence. Histamine-induced plasma leakage, which is PMN independent, was not affected by this treatment. F(ab)2 fragments of IB4 were as effective as the whole immunoglobulin G molecule in reducing PMN accumulation. The half-life of circulating IB4 in rabbits was found to be 11.5 hours. These results are consistent with in vitro studies that show that binding of PMNs to endothelium requires both expression of CD11/CD18 molecules and activation of the PMNs by agonists, and confirm that sites on CD11/CD18 that recognize endothelial cells are blocked by IB4. Other investigators have shown that injection of chemoattractants into the blood stream causes a rapid neutropenia associated with accumulation of PMNs in the lung. We find that intravenous treatment of animals with IB4 did not block the transient accumulation of PMNs in the lung induced by formyl-methionyl-leucyl-phenylalanine, suggesting that this accumulation occurs by a mechanism that does not require CD11/CD18 molecules.
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PMID:Relation of the CD11/CD18 family of leukocyte antigens to the transient neutropenia caused by chemoattractants. 197 22

In order to see whether leucocyte-derived adhesion molecules are involved in ischaemia and reperfusion, the total and differential leucocyte counts and expression of the LFA complex i.e. CD11a/CD18 (LFA-1), CD11b/CD18 (Mac-1) and CD11c/CD18 (p 150,95) were monitored before and after standard cold and heat tests in 8 females with Raynaud's Disease and 8 matched controls. All patients suffered from vasoconstriction during the cold test which, compared with controls, was associated with fewer granulocytes expressing significantly more CD11b/CD18 (Mac-1) integrin and a significant degree of neutropenia persisting during reperfusion. Leucocyte-endothelial adhesive interactions may therefore occur during ischaemia and reperfusion.
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PMID:Neutrophil-derived adhesion molecules in human digital ischaemia and reperfusion. 779 48

Blood contact with synthetic surfaces during cardiopulmonary bypass (CPB) causes a diffuse inflammatory reaction that includes neutrophil activation. The purpose of this study was to determine if inhibition of neutrophil adhesion with a new antiinflammatory agent NPC 15669 (N-(9H-(2,7-dimethylfluorenyl-9-methoxy)-carbonyl)-L-leucine) could reduce pulmonary injury in a porcine model of CPB. NPC 15669 blocks adherence of activated neutrophils by inhibiting upregulation of the Mac-1 (CD11b/CD18) adhesion molecule. Sixteen piglets underwent 2 hours of hypothermic CPB followed by 2 hours of observation; 8 received NPC 15669 (10 mg/kg intravenous bolus followed by 6 mg.kg-1.h-1 intravenous infusion) and 8 received equal volumes of vehicle. After 90 minutes of CPB, expression of neutrophil adhesion molecule subunit CD18 increased 118% in control piglets but only 36% in piglets treated with NPC 15669 (p < 0.01). Although neutropenia developed in all animals during CPB, lung tissue myeloperoxidase content was significantly lower in treated than in control animals 2 hours after CPB (94.9 +/- 10.4 versus 46.9 +/- 5.5 mumol.10 mg-1.min-1; p < 0.002). Free radical-mediated lipid peroxidation (quantitated by spectrophotometric assay of plasma conjugated dienes) was significantly reduced by treatment with NPC 15669 during and after CPB. Pulmonary function was better in NPC 15669-treated animals: 2 hours after CPB, pulmonary vascular resistance increased 477% in control piglets but only 140% in piglets receiving NPC 15669 (p < 0.03); arterial oxygen tension was significantly greater in piglets receiving NPC 15669 (428 +/- 33 mm Hg) than in controls (141 +/- 46; p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Inhibition of neutrophil adhesion during cardiopulmonary bypass. 790 44


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