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D M Center

Publications and source records attributed to D M Center.

At least 73 records · Page 4Linked to original sources
PubMed1990

Biologic activities of HIV-1 envelope glycoprotein: the effects of crosslinking.

We have examined the biologic activities of native and recombinant preparations of human immunodeficiency virus envelope glycoprotein (gp120), both derived from the HIV-1B strain. Antibody to gp120 was used to evaluate the effects of crosslinking gp120 on signalling by the CD4 receptor. Our results indicate that native and recombinant gp120 produce identical effects in our assay systems. Crosslinking gp120 amplified its chemoattractant activity for lymphocytes and monocytes and increased the peak intracellular calcium level, compared with binding of gp120 alone. The induction of inositol trisphosphate (IP3) production, induction of interleukin 2 receptors (IL2R), and inhibition of lymphocyte proliferation following treatment with gp120 were not enhanced by the addition of crosslinking antibody.

CD4-Positive T-Lymphocytes↗
PubMed1990

Components of the angiotensin system cause release of a neutrophil chemoattractant from cultured bovine and human endothelial cells.

Evidence suggests that angiotensin II can affect macrophage-mediated inflammatory responses; however, whether it can affect neutrophil-mediated inflammatory responses is not yet clear. We have previously demonstrated that components of the angiotensin system simulate bovine aortic and human umbilical vein endothelial cells to release a neutrophil chemoattractant. In the current study, we examined the effect of components of the angiotensin system on bovine and human pulmonary arterial and human aortic endothelial cells, and partially characterized this neutrophil chemoattractant. All endothelial cell types incubated with angiotensin II released neutrophil chemoattractant activity. This activity appeared within 1 min of exposure to angiotensin II, and was blocked by saralasin, an angiotensin II antagonist. The neutrophil chemoattractant also appeared after exposure to angiotensin I, but this effect required conversion to angiotensin II. Incubation with bradykinin, another substrate for angiotensin-converting enzyme, did not cause release of the neutrophil chemoattractant. Chemoattractant release was not inhibited by indomethacin but was blocked by diethylcarbamazine or 5,8,11,14-eicosatetraynoic acid. Following extraction, the neutrophil chemoattractant partitioned completely into the organic phase. High-pressure liquid chromatography demonstrated several peaks of chemoactivity, none of which co-eluted with known eicosanoid or phospholipid neutrophil chemoattractants. This study demonstrates that angiotensin II may influence neutrophil accumulation via production of neutrophil chemoattractant activity by vascular endothelial cells.

Angiotensin I↗
PubMed1990

Lymphocyte recruitment to the lung.

Lymphocyte recruitment in lymphoid tissues and inflammatory sites occurs in response to two events. The first is adherence of lymphocytes to specialized molecules expressed on the surface of appropriately stimulated vascular endothelial cells known as vascular addressins. The interaction occurs via specialized lymphocyte surface molecules known as homing receptors. There is considerable diversity among these molecules. At least three, and possibly four, different addressin-homing receptor pairs exist, regulating entry into peripheral lymph nodes, gut lymphoid tissue, BALT and intrathoracic lymphoid tissue, and inflamed synovium. Vascular addressins are expressed by specialized endothelial cells known as HEV. HEV are not found in normal lung parenchyma but may be induced to appear during an immune response. The mechanism for induction of HEV is unknown, although it may involve the action of inflammatory cytokines. It is not known whether separate endothelial cells exist with a propensity to develop into HEV or if any endothelial cells will develop into HEV if stimulated in the proper manner. Other accessory, lymphocyte-endothelium adhesion molecule pairs have been described, including LFA-1-ICAM-1 and CD4-HLA-DR. These molecules are induced by exposure of the endothelium to inflammatory cytokines, chiefly IFN-gamma. Thus, local humoral influences present during inflammation can alter the possibility of lymphocyte traffic through the endothelium by regulating the presence of lymphocyte adherence molecules. These processes have been documented to occur in the lung in normal homeostasis (e.g., BALT) and in disease (e.g., immunization with SRBC). After adherence, lymphocytes exit the circulation via amoeboid motility. This motility can be altered and enhanced through chemoattractant substances that act via surface receptors. The biochemical basis of cell motility is not entirely clear but appears to involve a link between the second messengers of receptor signaling and changes in the cytoskeleton, particularly actin filaments and microtubules. Like fibroblasts and smooth muscle cells, lymphocytes appear to respond to a number of "mitoattractants," substances that cause cell cycle entry and/or progression as well as enhanced motility. This relationship illustrates the integral relationship between cell motility and proliferation and suggests that the process of cell recruitment might also prime the recruitment cells to become activated to proliferate and perform effector function. Studies of lymphocyte-mediated lung disease confirm that antigen-specific as well as antigen-nonspecific lymphocytes are selectively recruited to the lung from the circulation during an inflammatory reaction in the lung.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Lymphocyte activation by HIV-1 envelope glycoprotein.

Cell activation by phytohaemagglutinin, phorbol ester and by the supernatant of phytohaemagglutinin-stimulated peripheral blood mononuclear cells induces the expression and cytopathic effects of latent human immunodeficiency virus type-1 (HIV-1) in vitro. The lymphocyte surface protein CD4 has been identified as a receptor for HIV-1 and binds the viral envelope glycoprotein (gp120). In the light of evidence indicating that one natural function of CD4 is as a growth factor receptor, we examined the ability of native gp120 to activate resting CD4-bearing lymphocytes. Our results indicate that gp120 has innate biological activity as a result of a specific interaction with CD4, inducing increases in intracellular levels of inositol trisphosphate and of calcium, and in interleukin-2 receptor expression and cell motility.

Calcium↗
PubMed1988

Structural and functional characterization of the human T lymphocyte receptor for insulin-like growth factor I in vitro.

Growth factor receptors for T lymphocytes, such as interleukin 2 and insulin, are present on activated but not resting T lymphocytes. We sought to determine if insulin-like growth factor I (IGF-I) could act as a growth factor for human T cells and to characterize its receptor on resting and activated cells. Recombinant IGF-I induced two separate functions. It was chemotactic for and increased incorporation of tritiated thymidine into both unactivated (resting) and mitogen-activated T cells. High-affinity 125I-IGF-I binding to human T cells was saturable with an apparent Kd of 1.2 +/- .6 X 10(-10) M for binding to activated T cells and 1.2 +/- .9 X 10(-10) for unactivated T cells. The calculated binding for activated cells was 330 +/- 90 and for resting cells 45 +/- 9 high-affinity receptor sites per cell. Affinity cross-linking of 125I-IGF-I to resting or activated T cells revealed a radioligand-receptor complex of 360,000 mol wt when analyzed by SDS-PAGE without reduction and complexes of 270,000 and 135,000 mol wt upon reduction; prior incubation with excess unlabeled IGF-I prevented formation of the 125I-IGF-I receptor complex. Our data suggest that both resting and activated T lymphocytes bear functional IGF-I receptors similar to those found in other tissues. These receptors may mediate T cell growth and chemotaxis.

Affinity Labels↗
PubMed1987

Lymphokine activation of T4+ T lymphocytes and monocytes.

The function of the T4 antigen, a marker for a differentiated T cell subset, is not well understood. Our previous observation that a chemoattractant human lymphokine, lymphocyte chemoattractant factor (LCF), which selectively induces motile responses in unactivated T4+ lymphocytes, led us to investigate whether LCF could also induce T4+ cell activation. Because LCF acts selectively on T4+ cells, we next determined whether the T4 antigen has a function in this LCF-induced cellular activation. A T4+ lymphocyte migratory response is induced by divalent anti-T4 antibody, but not by corresponding Fab fragments of the same antibody. Fab fragments of anti-T4 antibody, but not Fab fragments of anti-T3 antibody, block the migratory effect of both LCF and divalent anti-T4. Furthermore, LCF but not divalent anti-T4, evokes the expression of interleukin 2 (IL 2) receptors and HLA-DR antigen on T4+ lymphocytes in 24 hr. These effects are quantitatively similar to those observed by anti-T3 antibody activation. LCF-induced IL 2 receptor expression is blocked by co-incubation with anti-T4 antibody and anti-T4 Fab fragments, whereas anti-T3 activation is not inhibitable by anti-T4 Fab fragments. Because cultured monocytes express the T4 antigen, we investigated the action of LCF on cultured monocyte migration and HLA-DR expression. Induction of monocyte migration by LCF and anti-T4 antibody increases proportionally as T4 antigen expression increases in vitro. This enhanced migration is inhibitable by anti-T4 Fab fragments. Monocyte activation, as measured by augmented HLA-DR expression 24 hr after incubation with LCF, but not anti-T4 antibody, is quantitatively similar to the effects of interferon-gamma. Augmented HLA-DR expression is blocked by anti-T4 Fab fragments but not by antibody to interferon-gamma. These studies indicate that LCF interacts with T4+ lymphocytes and monocytes to induce migration and cellular activation.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

Chemotactic activity of porcine insulin for human T lymphocytes in vitro.

T lymphocytes bear insulin receptors only after activation and entry into the cell cycle. To determine whether cell motility is concomitant with growth factor action in T lymphocytes, we measured the chemotactic activity of porcine insulin (10(-11) to 10(-5) M) for T lymphocytes. We found that the chemotactic response of human T cells activated with phytohemagglutinin (PHA) to porcine insulin was increased over that of resting T cells, with a concomitant two log leftward shift in the dose response. CD4+ and CD8+ subsets responded identically. Checkerboard analysis showed insulin to be chemotactic, as well as chemokinetic. The nature and time course of acquisition of the dose-response shift suggest that chemotaxis may be signaled by insulin acting on high affinity insulin receptors. The chemotactic effect of insulin exemplifies the general chemotactic effect of growth factors for motile target cells, and may be a useful model for the study of chemotactic signaling in T lymphocytes.

Animals↗
PubMed1987

Effect of ambient oxygen on cultured endothelial cells from different vascular beds.

By the use of production of neutrophil chemoattractant activity as a marker, we investigated the responsiveness of endothelial cells of four different anatomic origins to altered ambient oxygen tension to determine whether genetic or conditioned variation existed. The ability of bovine aortic, bovine pulmonary arterial, bovine coronary arterial, and human umbilical vein endothelial cells incubated in decreased oxygen concentrations to release neutrophil chemoattractant activity was assessed. Bovine aortic, human umbilical vein, and bovine coronary arterial endothelial cells produce neutrophil chemoattractant activity in response to 10 or 3% ambient oxygen in vitro. In contrast, 0% ambient oxygen is required for appearance of neutrophil chemoattractant activity from pulmonary artery endothelial cells. These studies suggest that there may be genetic or conditioned variations in the response of endothelium from different vascular beds to decreased oxygen tensions. Furthermore, endothelial cells may play a role in neutrophil-mediated tissue injury during ischemia.

Animals↗
PubMed1986

Generation of, lipid neutrophil chemoattractant activity by histamine-stimulated cultured endothelial cells.

Endothelial cell-neutrophil interactions are an important aspect of inflammatory responses. Because vascular endothelial cells respond to the inflammatory mediator histamine, these studies determined whether histamine could induce endothelial cells to release substances that affect human neutrophil migration. Cultured bovine and human endothelial cells incubated with histamine released neutrophil chemoattractant activity within 1 min; peak levels were noted in 45 min. Cimetidine, an H2 receptor antagonist, blocked chemoattractant production, whereas diphenhydramine, an H1 receptor antagonist, did not. Cycloheximide did not inhibit release of chemoattractant activity, suggesting de novo protein synthesis was not necessary for its appearance. Extraction with acidified diethyl ether partitioned all neutrophil chemoattractant activity into the organic phase. The lipoxygenase pathway inhibitors, diethylcarbamazine and 5,8,11,14 eicosatetraynoic acid, inhibited generation of this lipophilic chemoattractant activity, whereas indomethacin, a cyclo-oxygenase inhibitor, did not. Resolution of the histamine-induced endothelial cell-derived chemoattractant activity by reverse-phase high pressure liquid chromatography yielded several peaks of chemoattractant activity, none of which co-eluted with leukotriene B4, platelet-activating factor, or two mono-hydroxyeicostetraenoic acids. These findings suggest that endothelial cells release lipid neutrophil chemoattractant activity that may play a role in inflammatory responses associated with histamine.

5,8,11,14-Eicosatetraynoic Acid↗
PubMed1986

A human T-T-cell hybridoma-derived lymphocyte chemoattractant factor.

Human T-T hybridomas were developed as a strategy for obtaining lymphokines that alter T-lymphocyte motility. Mitogen-stimulated human T lymphocytes were fused with cells of the human CEM lymphoma line and the supernatants derived from these fusion products were assessed for chemoattractant activity in a modified Boyden chamber assay. Supernatants from hybridoma 41B2 enhanced lymphocyte migration to 198 +/- 13% (mean +/- SEM) of control. Characterization by Sephadex G-100 molecular sieve chromatography revealed a single peak of chemoattractant activity corresponding to a molecular weight (MW) of 56,000. This activity eluted from a Sephadex QAE anion-exchange column at 4-6 mS. Subsequent isoelectric focusing in sucrose revealed an isoelectric point of 9.0-9.2. Fractions with activity after sequential molecular sieve and anion-exchange chromatography were concentrated, radiolabeled with 125I, and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Autoradiography revealed a band which corresponded to a MW of 14,000 (representing four similar monomeric chains) and to the region from which chemoattractant activity could be detected in eluates from slices of unstained gels run in parallel. The biological activity of this hybridoma-derived lymphocyte chemoattractant was abolished by treatment with trypsin and neuraminidase but was unaffected by heating to 56 degrees C. We conclude that certain human T-T-cell hybridomas constitutively elaborate a lymphocyte chemoattractant that appears to be physicochemically identical to a previously described human lymphokine, lymphocyte chemoattractant factor.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1986

Production of lymphocyte chemokinetic activity by stimulated alveolar macrophages.

While the presence of a lymphocytic parenchymal infiltrate is characteristic of several lung diseases, the mechanisms responsible for the focal accumulation of lymphocytes within the lungs remain unclear. Since alveolar macrophages secrete several substances that affect lymphocyte function, we examined supernatants of stimulated, cultured guinea pig alveolar macrophages for their ability to alter lymphocyte motility. Guinea pigs were immunized by footpad injection of ovalbumin (OVA) emulsified in complete Freund's adjuvant. Fourteen days later, alveolar macrophages were obtained by bronchial lavage or teasing the lung parenchyma, enriched by adherence to plastic, and incubated for 3 and 24 hours in culture medium alone or medium containing either latex beads, OVA, or human serum albumin (HSA). Conditioned medium was harvested and assayed for chemoattractant activity against rat splenic lymphocytes in modified Boyden chambers. Regardless of stimulus, there was no evidence of enhanced lymphocyte motility above control values in supernatants harvested at 3 hours. At 24 hours, alveolar macrophages from OVA-sensitized guinea pigs stimulated with latex or OVA generated significant amounts of lymphocyte migration stimulating activity (LCA) (250 +/- 25 and 247 +/- 24 percent of control migration, respectively) compared to cells incubated in medium alone or with HSA (162 +/- 23 and 147 +/- 14 percent, respectively). Antigen recognition appears to be related to the presence of cytophilic anti-OVA antibody on the surfaces of alveolar macrophages of sensitized guinea pigs. LCA is resistant to neuraminidase, chymotrypsin, and heating to 56 degrees C, and was chemokinetic for T-lymphocytes. it elutes from Sephadex G-100 in two regions: one at approximately 67,000 d, and a second at approximately 15,000 d. These studies indicate that following systemic immunization, the guinea pig alveolar macrophage can react to specific antigen or phagocytosis of inert particulates by secreting a chemokinetic factor for T-lymphocytes, and may play a role in the pathogenesis of some types of antigen-induced lung disease.

Animals↗
PubMed1985

Chemoattractant lymphokines specific for the helper/inducer T-lymphocyte subset.

The cellular content of T-lymphocyte-rich inflammatory sites is dependent in part on the in situ elaboration of chemoattractant factors. We have previously described three T-lymphocyte-specific chemoattractant lymphokines; a chemokinetic factor, lymphocyte chemoattractant factor (LCF, MW 56,000), and two distinct lymphocyte migration inhibitory factors (LyMIF75K, MW 75,000; and LyMIF35K, MW 35,000). These factors are produced by human T cells in response to antigen, concanavalin A, or histamine stimulation. In this communication, we report that LCF and LyMIF35K are produced by OKT8+ (suppressor/cytotoxic) and OKT4+ (helper/inducer) lymphocytes, respectively, and are selectively chemoattractant for the OKT4+ lymphocyte subset. LyMIF75K is produced by OKT4+ cells and inhibits both OKT4+ and OKT8+ lymphocyte migration. Production of LCF and LyMIF35K by infiltrating lymphocyte subsets may be one mechanism whereby unactivated helper/inducer T lymphocytes are selectively recruited to sites of inflammation.

Antibodies, Monoclonal↗
PubMed1985

Bovine and human endothelial cell production of neutrophil chemoattractant activity in response to components of the angiotensin system.

Although there is growing evidence that angiotensin II affects macrophage-mediated inflammatory responses, it is unclear whether it can affect neutrophil-mediated inflammatory responses. Because vascular endothelial cells are capable of releasing neutrophil chemoattractant activity, we attempted to determine whether components of the angiotensin system could affect neutrophil-mediated responses indirectly by stimulating endothelial cells to release neutrophil chemoattractant substances. Cultured bovine and human endothelial cells incubated with angiotensin II released neutrophil chemoattractant activity. This activity appeared within 1 minute of exposure to angiotensin II, and was blocked by saralasin, an angiotensin II antagonist. Angiotensin I also caused release of neutrophil chemoattractant activity, but its effect required conversion to angiotensin II. Bradykinin, another substrate for angiotensin-converting enzyme, did not stimulate appearance of chemoattractant. Chemoattractant generation was not inhibited by indomethacin but was blocked by diethylcarbamazine and 5,8,11,14-eicosatetraynoic acid. This study demonstrates that angiotensin II may influence neutrophil accumulation, via production of neutrophil chemoattractant activity by vascular endothelial cells.

5,8,11,14-Eicosatetraynoic Acid↗
PubMed1985

Induction of human T lymphocyte motility by interleukin 2.

Interleukin 2 (IL 2) is known to have multiple immunoenhancing activities that are related to its ability to promote the proliferation and the expression of effector functions of human T lymphocytes. We investigated the potential of IL 2 to induce human T lymphocyte migration. Unstimulated T cells did not respond to IL 2, but T cells exposed to dextran or phytohemagglutinin did respond to IL 2 concentrations from 0.01 to 10.0 U/ml, with significantly increased migration. This activity could be specifically blocked with anti-Tac antibody. Analysis of T lymphocyte subsets revealed that OKT4+ but not OKT8+ lymphocytes responded to IL 2 in the chemotaxis assay. Checkerboard analysis demonstrated that the IL 2-induced chemoattractant activity was predominantly chemotactic rather than chemokinetic in nature. The activity of IL 2 was compared with that of another chemoattractant lymphokine, lymphocyte chemoattractant factor, which was found to stimulate lymphocyte migration without prior exposure to mitogen, and which was not inhibited by anti-Tac. Our data suggest that the lymphocyte migratory response to IL 2 is under the control of the inducible receptor recognized by anti-Tac in a manner similar to the proliferative response to IL 2, but differs from proliferation in its OKT4+ cell specificity.

Adjuvants, Immunologic↗
PubMed1984

Modulation of lymphocyte migration by human lymphokines. III. Characterization of a lymphocyte migration inhibitory factor (LyMIF35K).

The lymphokine that augments the migration of nonsensitized T lymphocytes (LCF) has been observed to be predominantly a chemokinetic factor, suggesting that separate lymphocyte migration inhibitory lymphokine(s) might exist. Utilizing a modified Boyden chamber assay, lymphocyte migration inhibitory activity was identified in the culture supernatants of human nylon wool-nonadherent blood mononuclear cells stimulated with concanavalin A in vitro for 48 hr. Sephadex G-100 gel filtration chromatography of these culture supernatants was shown to contain two regions of noncytotoxic migration inhibitory activity for nonsensitized human blood lymphocytes and rat splenic lymphocytes. The 30-40,000 dalton inhibitory activity was further characterized and noted to be cationic by ion-exchange chromatography and isoelectric focusing (pI = 8.6). Its biologic activity was sensitive to neuraminidase and to heat treatment but not to trypsin. The migration inhibitory activity of this factor (LyMIF35K) was directly proportional to its ability to increase lymphocyte adherence.

Animals↗
PubMed1984

Thiourea causes endothelial cells in tissue culture to produce neutrophil chemoattractant activity.

We describe neutrophil chemoattractant activity that is produced by cultured bovine aortic and pulmonary arterial endothelial cells when incubated with thiourea, a substance that causes increased permeability pulmonary edema in animals. The chemoattractant activity was present in culture supernates and cell lysates of endothelial cells incubated with thiourea but was not present in untreated cells. Production of chemoattractant activity was not associated with cell death; viable cell counts and cell homogenate angiotensin converting enzyme levels were not affected, and Cr release was only slightly elevated after incubation with thiourea. At least 1.5 h of incubation with 0.5 mM thiourea was necessary for generation of neutrophil chemoattractant activity. Culture supernates from pulmonary vascular smooth muscle cells and lung fibroblasts did not show increased neutrophil chemoattractant activity after incubation with thiourea. The chemoattractant had both chemokinetic and chemotactic properties, was heat stable, and was extractable into organic solvents. Meclofenamate, a cyclooxygenase inhibitor, minimally inhibited chemoattractant production, whereas 5,8,11,14-eicosatetraynoic acid (ETYA), an inhibitor of both cyclooxygenase and lipoxygenase, completely abolished generation of chemoattractant activity, suggesting that the activity could be a product of arachidonic acid metabolism. These results demonstrate that endothelial cells can produce a substance(s) with neutrophil chemotactic activity. Production of neutrophil chemoattractant activity by endothelial cells could be important in polymorphonuclear leukocyte accumulation at injured vascular sites.

5,8,11,14-Eicosatetraynoic Acid↗
PubMed1984

Interstitial pulmonary fibrosis induced in hamsters by intratracheally administered chrysotile asbestos. Histology, lung mechanics, and inflammatory events.

The development of interstitial pulmonary fibrosis (IPF) is associated with persistent cellular infiltration and progressive connective tissue accumulation in the alveolar walls. To develop and characterize an animal model of IPF in which pulmonary fibrosis evolves slowly, as well as to develop an inexpensive, easily produced, model of asbestosis, Syrian golden hamsters received single intratracheal injections of either UICC chrysotile asbestos or saline. Animals were then examined at time points up to 180 days for pulmonary histologic and physiologic changes, cytologic characteristics of cells recovered by bronchoalveolar lavage, and spontaneous release of neutrophil chemoattractant activity by alveolar macrophages. Within days after asbestos treatment, hamsters developed a patchy bronchopneumonia centered around terminal airways, which progressed peripherally with time to involve the alveolar walls with persistent inflammation and the gradual development of interstitial and peribronchiolar fibrosis. These histologic changes were accompanied by physiologic findings of air-flow obstruction with air trapping. Bronchoalveolar lavage revealed a persistent neutrophilia that began within 24 h of asbestos treatment; this was associated with the spontaneous release of neutrophil chemotactic activity by cultured alveolar macrophages. In this animal model, pulmonary inflammation and fibrosis can be predictably produced by a single intratracheal instillation of chrysotile asbestos. It represents a useful tool for studying both asbestosis and pulmonary fibrosis in general.

Animals↗