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C W Smith

Publications and source records attributed to C W Smith.

At least 253 records · Page 14Linked to original sources
PubMed1991

Activated human polymorphonuclear leucocytes reduce rabbit papillary muscle function: role of the CD18 glycoprotein adhesion complex.

STUDY OBJECTIVE: The aim was to determine if human polymorphonuclear leucocytes activated by human recombinant C5a (hrC5a) reduce the contractile function of the isolated papillary muscle and if this response depends upon the functional integrity of the CD18 glycoprotein adhesion complex. DESIGN: Human neutrophils with or without pretreatment with monoclonal antibodies to the CD18 adhesion complex were added to organ baths containing isolated papillary muscles of the rabbit and activated with hrC5a. Changes in papillary muscle function were measured. EXPERIMENTAL MATERIAL: 52 right ventricular papillary muscles isolated from rabbit and neutrophils isolated from human whole blood were used. MEASUREMENTS AND MAIN RESULTS: Neither neutrophils nor hrC5a alone reduced papillary muscle function, but activation of neutrophils with hrC5a provoked reduction in myocardial contractility. This correlated with the degree of neutrophil stimulation, assessed by cell aggregation. Pretreatment of neutrophils with antibodies to the CD18 adhesion complex significantly attenuated the neutrophil induced contractile impairment. CONCLUSIONS: Activated human neutrophils can impair contractile function of papillary muscles, which is dependent upon adhesion of the leucocytes to the muscle via the CD18 complex.

Animals↗
PubMed1991

Inflammation in the course of early myocardial ischemia.

Experimental models of acute ischemic myocardial injury indicate that the inflammatory response after the ischemic event contributes to tissue damage. This is especially apparent with reperfusion of the ischemic tissue. In such models some therapeutic strategies designed to reduce neutrophil accumulation or function have resulted in apparently beneficial effects. Although such findings are encouraging, interventions into these pathological processes using specific molecular targets will require greater understanding of specific mechanisms. Current evidence indicates that potential sites of therapeutic intervention will be found in pathways leading to complement activation, generation of lipid-derived mediators, adhesion of neutrophils to endothelial cells and cardiac myocytes, and activation of neutrophil secretory processes releasing, for example, proteolytic enzymes and reactive oxygen. Understanding the dynamic interplay between the mediators, adhesion pathways, and secretory processes that results in myocardial damage will allow a rational approach to controlling the detrimental inflammatory consequences of ischemia and reperfusion.

Animals↗
PubMed1991

Alpha-tropomyosin mutually exclusive exon selection: competition between branchpoint/polypyrimidine tracts determines default exon choice.

We have used exons 2 and 3 of the rat alpha-tropomyosin gene to analyze the basis of mutually exclusive exon selection. The basis of the strict mutually exclusive behavior of this exon pair is enforced by the proximity of the exon 3 branchpoint to the 5' splice site of exon 2. With the exception of smooth muscle cells, exon 3 rather than exon 2 is incorporated into mRNA in all cell types. We show here, using both in vivo and in vitro cell-free systems, that this alternative exon selection is a consequence of general principles that govern 3' splice site selection. In the absence of exon 3, exon 2 is utilized efficiently in all cells. Selection of exon 3 is therefore the default result of a competition between exons 2 and 3 for the flanking constitutive splice sites. The basis of this competition is the relative strength of the polypyrimidine tract/branchpoint elements of the two exons. The major determinant of this splice site strength is the pyrimidine content adjacent to the branchpoint, and this involves no other sequence specificity. The branchpoint elements play an important but secondary role. The functional strengths of the different polypyrimidine tract/branchpoint combinations, as determined in cis competition assays, showed a perfect correlation with their binding affinities to a spliceosome component that interacts with the pre-mRNA in an ATP-independent manner. Selection of exon 3 in most cell types therefore reflects the preferential interaction of these splice site elements with constitutive splicing factors early in spliceosome assembly. The aspects of splice site selection analyzed here are likely to be of general applicability to constitutive and alternative pre-mRNA splicing.

Animals↗
PubMed1991

Immunodominant T-cell epitope on the F protein of respiratory syncytial virus recognized by human lymphocytes.

The lymphocyte proliferative responses to respiratory syncytial virus (RSV) were evaluated for 10 healthy adult donors and compared with proliferative responses to a chimeric glycoprotein (FG glycoprotein) which consists of the extracellular domains of both the F and G proteins of RSV and which is produced from a recombinant baculovirus. The lymphocytes of all 10 donors responded to RSV, and the proliferative responses to the whole virus were highly correlated with the responses to the FG glycoprotein. These data suggested that one or both of these glycoproteins of RSV were major target structures for stimulation of the human lymphocyte proliferative response among virus-specific memory T cells. The lymphocytes of four donors were evaluated further for their proliferative responses to a nested set of overlapping peptides modeled on the extracellular and cytoplasmic domains of the F protein of RSV. Strikingly, the lymphocytes of all 4 donors responded primarily to a region defined by a single peptide spanning residues 338 to 355, and the lymphocytes of 2 donors responded to an overlapping peptide spanning residues 328 to 342 also, thus defining a region of the F1 subunit within residues 328 to 355 that may circumscribe an immunodominant site for stimulation of human T cells from a variety of individuals. This region of the F protein is highly conserved among A and B subgroup viruses. As revealed by monoclonal antibody blocking studies, the lymphocytes responding to this antigenic site had characteristics consistent with T helper cells. Similar epitope mapping studies were performed with BALB/c mice immunized with the FG protein in which a relatively hydrophobic peptide spanning residues 51 to 65 within the F2 subunit appeared to be the major T cell recognition determinant. The data are discussed with respect to an antigenic map of the F protein and the potential construction of a synthetic vaccine for RSV.

Animals↗
PubMed1991

Neutrophil-induced liver cell injury in endotoxin shock is a CD11b/CD18-dependent mechanism.

To investigate the role of neutrophils (PMNs) and PMN-dependent adhesion molecules in the pathogenesis of liver injury in a model of endotoxin shock, male ICR mice received a dose of 700 mg/kg galactosamine and 100 micrograms/kg Salmonella abortus equi endotoxin. PMNs accumulated continuously in the liver, reaching values of 446 +/- 71 PMNs/50 high-power fields at 9 h (basal value 18 +/- 7). Plasma alanine aminotransferase activities as index of parenchymal cell injury did not change up to 5 h posttreatment (basal value 35 +/- 5 U/l) but increased to 1,950 +/- 460 U/l at 9 h. The formation of glutathione disulfide (GSSG) in plasma as an index of an extracellular oxidant stress also increased only at 9 h. Pretreatment of animals with monoclonal antibodies against the CD11b and CD18 subunits of the CD11/CD18 integrin family on the surface of the PMN reduced the number of PMNs in the liver by 50% and significantly attenuated liver injury and GSSG formation. An anti-CD11a and a nonbinding control antibody were ineffective. It is concluded that PMNs are actively involved in the pathogenesis of galactosamine and endotoxin shock and that at least in part the accumulation of PMNs, the subsequent oxidant stress, and the tissue injury in this model of experimental hepatitis are CD11b/CD18 (Mac-1) dependent.

Animals↗
PubMed1991

Neutrophil accumulation in ischemic canine myocardium. Insights into time course, distribution, and mechanism of localization during early reperfusion.

BACKGROUND: We have previously demonstrated that chemotactic factors released from the ischemic canine myocardium peak early during reperfusion and that they elicit neutrophil adherence reactions in vitro that are dependent on the CD18 glycoprotein family. In this study we investigated the hypothesis that neutrophil localization in ischemic canine myocardium in vivo occurs over a similar time course during early reperfusion and involves a CD18-dependent mechanism. METHODS AND RESULTS: We occluded the circumflex coronary artery for 1 hour in acute, open-chest dogs, followed by reperfusion for 1, 2, 3, or 4 hours. Regional myocardial blood flow was determined using radiolabeled microspheres, and localization was traced using technetium-99m-labeled autologous neutrophils. In the first hour of reperfusion, neutrophil localization occurred preferentially within the subendocardial region and was inversely related to flow. Neutrophil localization diminished across the ischemic myocardium from endocardium to epicardium but remained negatively related to flow in the midmyocardial region. Regardless of flow, little neutrophil localization occurred in the subepicardial region. Neutrophil localization was greatest in the first hour of reperfusion and diminished thereafter. By 4 hours of reperfusion, the rate of localization was markedly attenuated relative to 1 hour. Dogs given anti-CD18 monoclonal antibody R15.7 (1 mg/kg i.v.) before occlusion underwent 1 hour of occlusion followed by 1 hour of reperfusion. When compared with 1-hour reperfusion controls, the R15.7-treated dogs demonstrated significant attenuation of neutrophil localization in the subendocardial region. CONCLUSIONS: These data support the concepts that rapid neutrophil localization during reperfusion occurs within regions of previous myocardial ischemia and that neutrophils preferentially localize within the subendocardial region. The rate of neutrophil localization is greatest within the first hour after the initiation of reperfusion, and localization is, at least in part, CD18 dependent. Therapies directed against neutrophil-mediated reperfusion injury should be initiated with these considerations in mind.

Animals↗
PubMed1991

Hydrogen peroxide pretreatment of perfused canine vessels induces ICAM-1 and CD18-dependent neutrophil adherence.

BACKGROUND: Cytotoxic products of neutrophils (polymorphonuclear leukocytes, PMNs) contribute to ischemia-reperfusion injury of several tissues. Hydrogen peroxide (H2O2), one of the cytotoxic products of PMNs, also promotes the adherence of PMNs to cultured vascular endothelial cells in vitro. The present study was undertaken to determine if H2O2 also augmented adhesion of PMNs to intact vessels perfused ex vivo and to determine if H2O2-induced PMN adherence to intact canine carotid arteries and external jugular veins or to cultured canine venous endothelium is mediated by specific adherence ligands on the neutrophil and/or the endothelium. METHODS AND RESULTS: Vessels were perfused for 20 minutes with oxygenated Krebs-Henseleit bicarbonate buffer with and without H2O2, washed with buffer alone, and then exposed to 111In-labeled isolated PMNs (10(7) cells/vessel) under static conditions for up to 20 minutes before being washed again. Residual radioactivity retained by the washed vessel was counted as an index of PMN retention. The adherence of unlabeled PMNs to cultured endothelial cells was determined by a visual assay method after pretreatment of the endothelium with H2O2 for brief periods followed by washing. Perfusion of vessels with H2O2 produced a transient, concentration-dependent increase in PMN adhesion to both canine carotid arteries and external jugular veins that was two to four times that of control values at 1 mmol/l and declined at higher H2O2 concentrations. Peak retention of PMNs by canine carotid arteries occurred 10 minutes after exposure to 1 mmol/l H2O2 and then rapidly declined to control values; this effect was replicated by a second 20-minute exposure of canine carotid arteries to 1 mmol/l H2O2 60 minutes after the first exposure. Scanning and transmission electron microscopy revealed not only adherence of PMNs to but migration through the vascular endothelium of the carotid artery after H2O2 perfusion. The endothelium was intact in H2O2-treated arteries not exposed to PMNs. H2O2-induced PMN retention was completely inhibited by addition of catalase or the hydroxyl radical scavenger dimethylthiourea to the perfusate by incubation of the PMN with a monoclonal antibody (Mab) against CD18 (R15.7) or by perfusion of the H2O2-treated vessel with CL18/6, a Mab against canine ICAM-1 (intercellular adhesion molecule-1). Similar effects of Mabs on PMN adhesion to H2O2-pretreated cultured endothelium were noted. The retention of PMNs by vessels mechanically denuded of endothelial cells was markedly increased. H2O2 pretreatment of these vessels did not further augment PMN adherence, and no inhibitory effect of R15.7 was noted. Incubation of carotid arteries and PMNs with a specific platelet-activating factor antagonist, WEB2086, completely inhibited the H2O2-induced increased PMN retention by these vessels. CONCLUSIONS: These results indicate that H2O2 in the absence of evidence for permanent endothelial cell injury, can induce a transient, reversible, platelet-activating factor-dependent adherence of PMNs to vessels by mechanisms that depend on an intact endothelium and involve CD18 on the PMN and ICAM-1 on the endothelium.

Animals↗
PubMed1991

Chemotactic factors regulate lectin adhesion molecule 1 (LECAM-1)-dependent neutrophil adhesion to cytokine-stimulated endothelial cells in vitro.

Monoclonal antibodies recognizing CD18, CD11a, CD11b, and neutrophil lectin adhesion molecule 1 (LECAM-1), i.e., the human homologue of the murine MEL-14 antigen, were used to assess the relative contribution of these glycoproteins to neutrophil-endothelial adhesion. Under static conditions, the adhesion of neutrophils to IL-1-stimulated human umbilical vein endothelial cell (HUVEC) monolayers was inhibited by antibodies to CD18, CD11a, and the neutrophil LECAM-1, and the effect of combining anti-LECAM-1 and anti-CD11a was almost additive. Under flow at a wall shear stress 1.85 dyn/cm2, a condition where CD18-dependent adhesion is minimal, anti-LECAM-1 inhibited adhesion by greater than 50%. Chemotactic stimulation of neutrophils induced a rapid loss of LECAM-1 from the neutrophil surface, and the level of neutrophil surface LECAM-1 was closely correlated with adhesion under flow. Neutrophils contacting the activated endothelial cells for 30 min lost much of their surface LECAM-1, a phenomenon induced by a soluble factor or factors released into the medium by the stimulated monolayers, and a high percentage migrated through the HUVEC monolayer. This migration was almost completely inhibited by anti-CD18, but was unaffected by antibodies to neutrophil LECAM-1. These results support the concept that LECAM-1 is a neutrophil adhesion molecule that participates in the adherence of unstimulated neutrophils to cytokine-stimulated endothelial cells under conditions of flow, and is then lost from the neutrophil surface coincident with the engagement of CD18-dependent mechanisms leading to transendothelial migration.

Adult↗
PubMed1991

Adherence of neutrophils to canine cardiac myocytes in vitro is dependent on intercellular adhesion molecule-1.

The adhesiveness of isolated canine cardiac myocytes for neutrophils is greatly increased by stimulation with cytokines such as tumor necrosis factor alpha (TNF alpha). Since this adhesion is significantly inhibited by an anti-CD18 MAb, experiments were performed to test the hypothesis that the newly expressed adhesion molecule on the cardiac myocytes was intercellular adhesion molecule-1 (ICAM-1). A newly developed MAb, CL18/6, was found to exhibit the functional and binding characteristics with canine neutrophils and canine jugular vein endothelial cells expected of an antibody recognizing ICAM-1. MAb CL18/6 also bound to isolated cardiac myocytes after stimulation of the myocytes with cytokines, and it blocked by greater than 90% the adhesion of neutrophils to stimulated myocytes. A partial cDNA clone for canine ICAM-1 was isolated, and ICAM-1 mRNA was found to be increased in both endothelial cells and cardiac myocytes after cytokine stimulation. Cytokines that both increased the CL18/6-inhibitable adhesion of neutrophils to myocytes and induced expression of ICAM-1 were IL-1 beta, TNF alpha, and LPS. These results are consistent with the conclusion that canine endothelial cells and cardiac myocytes express ICAM-1 in response to cytokine stimulation, and that ICAM-1 functions as an adhesive molecule for neutrophils on both cell types.

Animals↗
PubMed1991

Role of endothelial-leukocyte adhesion molecule 1 (ELAM-1) in neutrophil-mediated lung injury in rats.

Two murine monoclonal antibodies (CL-3 and CL-37, both F(ab')2) to human endothelial-leukocyte adhesion molecule-1 (ELAM-1) were found to react immunohistochemically with rat pulmonary artery endothelial cells that had been pretreated with tumor necrosis factor (TNF alpha). CL-3, but not CL-37, blocked in vitro adherence of neutrophils to TNF alpha-treated endothelial cells and the killing of TNF alpha-treated rat endothelial cells by phorbol ester activated neutrophils. In rats treated systemically with CL-3, there was a 70% reduction in accumulation of neutrophils in glycogen-induced peritoneal exudates. Treatment of animals with CL-37 anti-ELAM-1 did not reduce neutrophil accumulation under the same conditions. When IgG immune complex deposition was induced in dermis and in lungs of rats, treatment with CL-3 anti-ELAM-1 markedly reduced vascular injury as measured by changes in vascular permeability (leakage of 125I-albumin) and hemorrhage (extravasation of 51Cr-red blood cells). The protective effects of CL-3 anti-ELAM-1 were related to greatly diminished recruitment of neutrophils (as assessed morphologically, by tissue extraction of myeloperoxidase, and by retrieval, via bronchoalveolar lavage, of neutrophils from lung). CL-37 had no protective effects in vivo after deposition of immune complexes in lung. Using either CL-3 or CL-37 anti-ELAM-1, immunohistochemical analysis of lungs undergoing IgG immune complex-induced injury revealed a striking upregulation of ELAM-1 in the lung vasculature (venules and interstitial capillaries), with a peak intensity developing between 3 and 4 h after deposition of immune complexes in lung. Vascular beds of spleen, liver, and kidney failed to show upregulation of ELAM-1 under these same conditions. The immunohistochemical reactivity of rat lung was abolished if the anti-ELAM-1 preparation was first absorbed with monolayers of human umbilical vein endothelial cells that had been pretreated with TNF alpha. Untreated human endothelial cells failed to cause loss of lung reactivity of the anti-ELAM-1 preparation. These data indicate that ELAM-1 is upregulated in the pulmonary vasculature of rats during deposition of immune complexes and that ELAM-1 appears to play an obligate role in the recruitment of neutrophils.

Animals↗
PubMed1991

Endothelial leukocyte adhesion molecule-1 mediates antigen-induced acute airway inflammation and late-phase airway obstruction in monkeys.

This study examines the role of endothelial leukocyte adhesion molecule-1 (ELAM-1) in the development of the acute airway inflammation (cell influx) and late-phase airway obstruction in a primate model of extrinsic asthma. In animals sensitive to antigen, a single inhalation exposure induced the rapid expression of ELAM-1 (6 h) exclusively on vascular endothelium that correlated with the influx of neutrophils into the lungs and the onset of late-phase airway obstruction. In contrast, basal levels of ICAM-1 was constitutively expressed on vascular endothelium and airway epithelium before antigen challenge. After the single antigen exposure, changes in ICAM-1 expression did not correlate with neutrophil influx or the change in airway caliber. This was confirmed by showing that pretreatment with a monoclonal antibody to ICAM-1 did not inhibit the acute influx of neutrophils associated with late-phase airway obstruction, whereas a monoclonal antibody to ELAM-1 blocked both the influx of neutrophils and the late-phase airway obstruction. This study demonstrates a functional role for ELAM-1 in the development of acute airway inflammation in vivo. We conclude that, in primates, the late-phase response is the result of an ELAM-1 dependent influx of neutrophils. Therefore, the regulation of ELAM-1 expression may provide a novel approach to controlling the acute inflammatory response, and thereby, affecting airway function associated with inflammatory disorders, including asthma.

Acute Disease↗
PubMed1991

Exercise. Practical treatment for the patient with depression and chronic fatigue.

Exercise should be part of everyone's lifestyle, but may be a particularly important part of the treatment of patients with depression and chronic fatigue. It will reliably and consistently decrease feelings of tiredness and despondency, although it is seldom sufficient as a sole treatment intervention for such patients. When initiating an exercise program, a baseline assessment should be followed by an exercise prescription and an appropriate degree of patient education about exercise physiology. This should be followed, in addition to other treatment interventions, by regular follow-up visits to make appropriate adjustments; provide encouragement and motivation to continue; monitor weight, body fat, and nutrition; and assess the effectiveness of the program on the underlying problem.

Chronic Disease↗
PubMed1990

Impaired transendothelial migration by neonatal neutrophils: abnormalities of Mac-1 (CD11b/CD18)-dependent adherence reactions.

In order to evaluate the functions of lymphocyte function antigen-1 (LFA-1) (CD11a/CD18) and Mac-1 (CD11b/CD18) on neonatal neutrophils, we examined neutrophil adhesion to and migration through human umbilical vein endothelial cell (HUVEC) monolayers in vitro. Transendothelial migration of adult neutrophils was greatly enhanced by preincubation of HUVEC with interleukin-1 (IL-1). This migration was significantly inhibited by monoclonal antibodies (MoAbs) against LFA-1 (CD11a) and Mac-1 (CD11b) subunits. Migration of neonatal neutrophils was markedly diminished compared to adult neutrophils, and MoAbs against LFA-1 further reduced migration. In contrast, anti-Mac-1 MoAb was not inhibitory. Adhesion of adult neutrophils was significantly enhanced by prestimulation of HUVEC with IL-1, and was significantly inhibited by MoAbs against LFA-1. Adhesion of neonatal neutrophils was near adult levels and comparably inhibited by anti-LFA-1 MoAb. In addition, adhesion of neonatal and adult neutrophils to purified ICAM-1 in artificial planar membranes was comparable and almost completely inhibited by anti-LFA-1 MoAb. Chemotactic stimulation induced Mac-1-dependent adhesion of adult neutrophils to endothelial cells, purified intercellular adherence molecule-1 (ICAM-1) and protein-coated glass. In marked contrast, adhesion of neonatal neutrophils to these substrates was not significantly increased by chemotactic stimulation. These findings indicate that diminished transendothelial migration by neonatal neutrophils is related to abnormal interactions of Mac-1 with ICAM-1 and possibly other endothelial ligands. These functional deficits may contribute to impaired inflammation and infectious susceptibility in human neonates.

Aging↗
PubMed1990

Mac-1 (CD11b/CD18) mediates adherence-dependent hydrogen peroxide production by human and canine neutrophils.

Human neutrophils exposed to protein-coated polystyrene or cultured endothelial monolayers produce large quantities of H2O2 in response to soluble stimuli that elicit little or no secretion of reactive oxygen species from cells in suspension. To characterize the mechanisms involved in this adherence-dependent respiratory burst, we have investigated the possible role of one integrin known to participate in the adhesion of neutrophils to endothelial cells, CD11b/CD18 (Mac-1). H2O2 production was examined with chemotactic factor-stimulated human and canine neutrophils exposed to protein-coated surfaces and cultured human and canine endothelial cells. The two protein-coated surfaces used were type I collagen-coated glass or plastic, a surface to which neither human nor canine neutrophils adhered, and keyhole limpet hemocyanin (KLH)-coated glass or plastic, a surface to which human and canine neutrophils adhered only after chemotactic stimulation. FMLP-stimulated human neutrophils and platelet activating factor-stimulated canine neutrophils failed to produce detectable H2O2 when in contact with type I collagen, but secreted large amounts of H2O2 when adherent to KLH or endothelial cell monolayers. FMLP-stimulated neutrophils from patients with CD18-deficiency failed to adhere to any of these surfaces and failed to produce H2O2 under these conditions. mAb reactive with CD18 and CD11b were equally effective in markedly inhibiting the adhesion of normal human neutrophils to these surfaces and markedly inhibited the production of H2O2. A mAb reactive with CD18 blocked adhesion of stimulated canine neutrophils, and mAb directed against both CD18 and CD11b blocked H2O2 production by canine neutrophils on KLH and endothelium. A nonbinding mAb and a mAb reactive with CD11a did not inhibit H2O2 production of human cells on KLH or endothelial monolayers, and nonbinding and binding control mAb did not inhibit H2O2 production by canine neutrophils. These results indicate that Mac-1 (CD11b/CD18) can mediate adhesion-dependent H2O2 production by human and canine neutrophils exposed to chemotactic factors.

Antibodies, Monoclonal↗
PubMed1990

Subcellular distribution and mobilization of MAC-1 (CD11b/CD18) in neonatal neutrophils.

The CD11b/CD18 (Mac-1) heterodimeric surface glycoprotein contributes to a broad range of adherence-dependent neutrophil inflammatory functions. Previous investigations have indicated that diminished expression or regulation of Mac-1 may underlie abnormalities of stimulated adhesion and chemotaxis of neonatal neutrophils in vitro and inflammatory deficits in human neonates. To define the pathogenic mechanisms contributing to these findings, we compared the distribution and translocation of Mac-1 in subcellular fractions of neonatal and adult neutrophils before and after chemotactic stimulation. The total cell content of Mac-1 and the proportions of Mac-1 in beta fractions (vitamin B12 binding protein-rich granules), pre-gamma fractions (gelatinase-rich granules), or gamma fractions (plasma membrane) of neonatal neutrophils were comparable with those of adult neutrophils. However, after stimulation with N-formyl-methionyl-leucyl-phenylalanine (FMLP; 10 nmol/L, 37 degrees C, 15 minutes), neonatal neutrophils demonstrated (1) diminished translocation of Mac-1 from pre-gamma fractions (P less than .05), and (2) diminished surface expression of Mac-1 (P less than .05), as compared with healthy adult neutrophils. As shown in enzymatic and immunochemical assays, neonatal cells contained significantly (P less than .01) diminished levels of neutrophil gelatinase. In response to FMLP (0.1 to 10 nmol/L, 37 degrees C, 15 minutes), neonatal suspensions also released significantly (P less than .001) less gelatinase, as compared with adult neutrophil suspensions. These observations demonstrate that diminished mobilization of Mac-1 from gelatinase-rich granular pools in neonatal neutrophils is associated with abnormal surface expression of this glycoprotein after chemotactic stimulation. This abnormality may contribute, in part, to abnormal migratory properties of neonatal neutrophils in response to inflammatory stimuli.

Antigens, Differentiation↗
PubMed1990

Effect of venous shear stress on CD18-mediated neutrophil adhesion to cultured endothelium.

The CD11/CD18 family of glycoproteins has been identified as a mediator of a number of adhesive interactions crucial to inflammatory responses. Using a monoclonal antibody (MoAb) against CD18 (TS1/18), the role of these molecules in polymorphonuclear neutrophil (PMNL) adhesion to cultured primary human umbilical vein endothelial cells (HUVEC) was examined under venous flow conditions. Incubation of PMNL with TS1/18 (anti-CD18) did not inhibit PMNL adhesion to interleukin-1 (IL-1)-treated HUVEC at 2.0 dynes/cm2 (TS1/18-treated 305 +/- 58 PMNL/mm2 v 334 +/- 63 PMNL/mm2 on control). Furthermore, incubation of HUVEC with R6.5.D6, an MoAb against intercellular adhesion molecule-1 (ICAM-1) did not significantly inhibit PMNL adhesion to IL-1-treated HUVEC at 2.0 dynes/cm2 (P greater than .3). In contrast to the lack of inhibition of adhesion under conditions of flow, incubation of PMNL with TS1/18 reduced PMNL adherence in static adhesion assays. PMNL migration beneath HUVEC monolayers has been shown to be stimulated by 4-hour IL-1 treatment. TS1/18 and R6.5.D6 significantly inhibited migration of PMNL beneath IL-1-treated HUVEC monolayers under flow conditions by slightly more than 80% (P less than .005). In flow experiments with CD18-deficient PMNL, virtually no transendothelial migration was observed. The effect of FMLP (10(-8) mol/L) on PMNL adhesion to untreated HUVEC at wall shear stresses ranging from 0.25 to 2.0 dynes/cm2 was also investigated. FMLP had little effect on PMNL adherence at shear stresses above 0.5 dynes/cm2 (P greater than .45). In response to FMLP exposure at lower wall shear stresses, PMNL adherence to untreated HUVEC increased 6.9-fold at 0.5 dynes/cm2 (P less than .001). At 0.25 dynes/cm2, FMLP stimulation increased PMNL adherence to untreated HUVEC 6.5-fold compared with controls (P less than .005), and FMLP failed to make CD18-deficient PMNL more adherent. In experiments with PMNL pretreated with TS1/18 (anti-CD18), there was a 67% inhibition of FMLP-stimulated adhesion at 0.5 dynes/cm2 (P less than .025). The upper threshold of CD18-mediated PMNL adhesion appears to be between 0.5 and 1.0 dyne/cm2. Above these wall shear stresses, the initial attachment of PMNL to cultured endothelium was mediated almost exclusively by CD18-independent mechanisms. By simulating some of the flow parameters in the microcirculation with well-characterized shear forces, PMNL adhesion by CD18-independent and dependent mechanisms can be differentiated. These data also indicate that CD18 is an important mediator of transendothelial migration by PMNL, which have attached to the endothelium by a CD18-independent mechanism.

CD18 Antigens↗