Biomedical subjects

A Kapp

Publications and source records attributed to A Kapp.

At least 199 records · Page 11Linked to original sources

PubMed1991

Effect of tumour necrosis factor alpha in vivo on human granulocyte oxidative metabolism.

Tumour necrosis factor alpha (TNF alpha) effectively stimulates the oxidative metabolism of human PMN in vitro. Moreover, preincubation of PMN with TNF alpha has been shown to result in an altered response of the target cells to subsequent stimulation. In the present study the response of PMN to stimulation in vitro was investigated in patients with metastasizing malignant melanoma receiving bolus injections of recombinant human TNF alpha as therapy. TNF alpha was given daily for 5 days. Blood samples were taken prior to TNF alpha administration on days 1 to 4 and on day 8. Lucigenin-enhanced chemiluminescence (CL) was used as a sensitive measure of granulocyte oxidative metabolism. PMN were stimulated with TNF alpha, TNF beta, GM-CSF, PMA, opsonized zymosan and f-met-leu-phe. A significant increase in CL responses was detected upon stimulation with TNF alpha, TNF beta and PMA from day 1 to day 3, whereas no significant changes were observed for the background activity or when GM-CSF or opsonized zymosan were used as stimuli. On day 4 all CL responses returned to the day 1 starting level. A further significant decrease was observed on day 8 upon stimulation with TNF alpha, TNF beta and GM-CSF. In contrast, the effect induced by f-met-leu-phe reached a maximum on day 4, but the CL response was found to be at the starting level on day 8. The results indicate that TNF alpha induces significant changes in PMN response to distinct stimuli in vivo. Moreover, it may be possible that continuous daily infusions with TNF alpha induce a hyposensitization of PMN oxidative metabolism.

Acridines↗

PubMed1991

Eosinophil cationic protein in sera of patients with atopic dermatitis.

Patients with atopic dermatitis frequently show elevated blood eosinophil counts, and eosinophil-derived major basic protein has been demonstrated in the eczematous skin from patients with atopic dermatitis. To evaluate further the role of eosinophils in the pathogenesis of atopic dermatitis, the concentration of eosinophil cationic protein was measured in serum samples of 42 patients with moderate to severe disease. The results were compared with those obtained in 32 patients with psoriasis with (n = 9) or without (n = 23) a history of inhalant allergy, 12 patients with a history of pseudoallergic reactions to acetylsalicylic acid, 14 patients with a history of inhalant allergy, and 31 nonatopic healthy control subjects. Eosinophil cationic protein levels were significantly increased in the serum of patients with atopic dermatitis (p less than or equal to 0.005) and patients with a history of pseudoallergic reactions to acetylsalicylic acid (p less than or equal to 0.01). There was no significant difference between eosinophil cationic protein levels in patients with psoriasis or a history of inhalant allergy and in control subjects. Moreover, eosinophil cationic protein levels did not differ significantly in psoriasis patients with or without inhalant allergy. These studies support the concept of an active participation of eosinophils in atopic dermatitis and point to a possible role for eosinophils in pseudoallergy.

Adolescent↗

PubMed1991

Increased IL-6 production by monocytes and keratinocytes in patients with psoriasis.

Interleukin-6 (IL-6) is a multifunctional inflammatory cytokine that is produced by monocytes and keratinocytes upon stimulation. Because psoriasis is a skin disease characterized by a hyperproliferative activity of keratinocytes and an inflammatory infiltrate, in the present study IL-6 production of monocytes and keratinocytes of patients with psoriasis was investigated. Peripheral blood mononuclear cells (PBMC) derived from psoriatics, atopics, and healthy controls were incubated for 24 h and, subsequently, supernatant IL-6 activity was measured using an IL-6-dependent hybridoma cell line (B9). Compared to controls and atopics, PBMC of psoriatics produced significantly increased amounts of biologically active IL-6. These findings were also confirmed by Western blot analysis using a specific antiserum directed against IL-6. Moreover, when the sera of the same patients were tested for IL-6 activity, sera of psoriatics contained significantly elevated amounts of circulating IL-6 in comparison to samples from atopics and healthy controls. In contrast to normal or uninvolved skin, keratinocytes in psoriatic lesions were remarkably positive for IL-6 as detected by immunohistochemistry and in situ hybridization. In addition, IL-6 also was found to induce its own synthesis and release by monocytes. These findings indicate that keratinocytes and monocytes in psoriasis are activated to produce increased amounts of IL-6, which may be one of the mediators involved in the regulation of both local and systemic inflammatory reactions occurring in skin diseases such as psoriasis.

Adult↗

PubMed1991

55-kd tumor necrosis factor receptor is expressed by human keratinocytes and plays a pivotal role in regulation of human keratinocyte ICAM-1 expression.

Tumor necrosis factor alpha (TNF alpha) is a potent modulator of human keratinocyte intercellular adhesion molecule-1 (ICAM-1) expression. TNF alpha is known to exert its biologic effects by binding to specific cell-surface receptors. Two distinct TNF binding molecules, the 55-kd and the 75-kd TNF receptor (TNFR) recently have been found to be expressed by human cells. These two receptor types are independently regulated and differ markedly in their intracellular regions, indicating functional dichotomy. In order to gain further insight into the mechanisms underlying ICAM-1 regulation in human keratinocytes, in the present study, the receptor molecules mediating TNF alpha induced ICAM-1 upregulation in human keratinocytes was defined. Human keratinocyte TNFR expression was assessed using monoclonal antibodies that specifically recognize the 55-kd or the 75-kd TNFR. Using FACS analysis, normal (HNK) as well as transformed (KB) human keratinocytes were found to react with anti-55-kd TNFR, but not anti-75-kd TNFR antibodies. These immunofluorescence data were confirmed by Northern blot analysis revealing clearly detectable amounts of mRNA specific for the 55-kd TNFR in KB cells. Incubation of human keratinocytes with anti-55-kd TNFR antibodies at 37 degrees C for 24 h increased ICAM-1 expression in a TNF alpha-like fashion. Moreover, the well known synergistic effect of IFN gamma plus TNF alpha on keratinocyte ICAM-1 induction could be mimicked by stimulation of cells with IFN gamma plus anti-55-kd TNFR antibodies. Synergistic ICAM-1 induction was not associated with increased expression of the 55-kd TNFR in IFN gamma-stimulated human keratinocytes. These studies indicate that human keratinocytes express the 55-kd TNF receptor and that this surface molecule may play an important role in regulation of human keratinocyte ICAM-1 expression.

Binding Sites, Antibody↗

PubMed1991

Interleukin-5-induced granulocyte activation in atopic patients.

The effect of recombinant human and murine interleukin-5 (IL-5) on granulocytes was investigated in patients with atopic dermatitis (AD) and allergic rhinitis and compared with those from patients with plaque psoriasis and normal non-atopic controls. Granulocyte activation was measured as lucigenin-dependent chemiluminescence (CL) and release of eosinophil cationic protein (ECP) as well as by scanning- and transmission-electron microscopy (EM) and the ultrastructural detection of production of H2O2. A significant direct effect of both human and murine IL-5 on granulocyte oxidative metabolism could only be detected in those patients with AD and allergic rhinitis. Also, as compared to normal controls, significantly increased CL responses were observed in these patients with stimulation with other granulocyte-activating cytokines, particularly GM-CSF. In patients with psoriasis there was no significant increase in response to stimulation with TNF alpha, TNF beta or GM-CSF, but IL-5 induced slight but significant CL responses in the granulocytes. None of the cytokines tested significantly stimulated the release of ECP in any of the groups. Ultrastructural studies showed that stimulation with human as well as murine IL-5 produced significant morphological changes in both eosinophils and polymorphonuclear neutrophilic granulocytes from the patients with AD. Production of H2O2 was visualized at the luminal part of the intracytoplasmic vesicles of the granulocytes and at the points of contact between the cells. On morphometric analysis, almost all the polymorphonuclear neutrophils in the patients with AD appeared to be activated, whereas only some of these cells in the normal controls showed signs of activation.

Animals↗

PubMed1991

Effect of the leukotriene receptor antagonists FPL 55712, LY 163443, and MK-571 on the elimination of cysteinyl leukotrienes in the rat.

1. Leukotriene elimination via bile and urine is an important mechanism of inactivation for these potent lipid mediators. We investigated whether the elimination of cysteinyl leukotrienes is a target for the action of leukotriene receptor antagonists. 2. Experiments were performed in male rats under deep thiopentone anaesthesia. The bile duct and the urinary bladder were cannulated. Tritium labelled leukotrienes and leukotriene receptor antagonists were given via central venous catheters. Elimination of leukotrienes produced in vivo was studied following stimulation of endogenous leukotriene biosynthesis by operative trauma. 3H-leukotriene metabolites were identified by h.p.l.c. analysis. Leukotrienes produced in vivo were measured by combined use of h.p.l.c. and RIA. 3. Under control conditions, 49 +/- 12% of the injected 3H-leukotriene radioactivity was recovered in bile and 1 +/- 0.8% in urine within 90 min. Operative trauma resulted in initial hepatobiliary secretion of 887 +/- 206 pmol kg-1 h-1 of the endogenous leukotriene metabolite N-acetyl leukotriene E4 (LTE4NAc). 4. FPL 55712 strongly inhibited hepatobiliary elimination of 3H-leukotriene radioactivity in a dose-dependent manner after i.v. injection of [3H]-LTC4, [3H]-LTD4 or [3H]LTE4, respectively. Biliary [3H]-LTD4 was reduced most effectively. The leukotriene antagonist potently prevented biliary elimination of LTE4NAc produced in vivo. Bile flow and elimination from blood into bile of [3H]-ouabain were also impaired by FPL 55712, but to a lesser extent. 5. LY 163443 reduced biliary [3H]-LTD4 after i.v. administration of [3H]-LTD4. However, the total elimination of 3H-leukotriene metabolites into bile was not significantly inhibited by the drug. 6. MK-571 reduced the biliary concentration of tracer after administration of 3H-leukotrienes most potently with respect to [3H]-LTD4. In contrast, the total recovery of 3H-leukotrienes in bile tended to increase. This is explained by a drug-induced increase in bile flow. 7. Urinary elimination of 3H-leukotrienes, quantitatively less important in the rat, was not significantly influenced by the leukotriene receptor antagonists. Recovery of 3H-leukotriene radioactivity in liver and kidneys was quantitatively insignificant. 8. From our data, we conclude that leukotriene receptor antagonists have the potential to affect leukotriene elimination by a mechanism not necessarily related to receptor blockade. Inhibition of elimination by the receptor antagonists may prolong the biological half life of leukotrienes. This effect may counteract the antagonistic properties of these drugs.

Acetophenones↗

PubMed1991

Effect of Ca-panthotenate on human granulocyte oxidative metabolism.

Activated granulocytes play an important role in propagation of the inflammatory response by production of reactive oxygen species and release of their granule content. Hyperactivation of these cells is suggested to result in deterioration of wound healing and, probably, increase of cicatrization. Pantothenic acid and its stable salt form, Ca-Panthotenate, were shown to significantly improve surgical wound healing. Therefore, in the present study the modulating effect of Ca-pantothenic acid to subsequent stimulation with a variety of stimuli was investigated on isolated human PMN using functional assay systems: Lucigenin-dependent chemiluminescence (CL), release of myeloperoxidase (MPO). Ca-Panthotenate significantly inhibited the CL response of PMN upon stimulation with the chemotactic petide f-met-leu-phe, the tumor promotor PMA, and the granulocyte activating cytokines GM-CSF and TNF alpha at a concentration range of 5 to 50 mM, but not upon stimulation with opsonized zymosan. Moreover, Ca-Panthotenate significantly inhibited the release of myeloperoxidase from PMN upon stimulation with f-met-leu-phe at a concentration of 5 mM. In contrast, Ca-Panthotenate did not directly activate PMN in the assay systems tested. These in vitro results support the concept of an anti-inflammatory action of Ca-Panthotenate in vivo.

Cell Degranulation↗

PubMed1991

Production of interleukin-2 by mononuclear cells in vitro in patients with atopic dermatitis and psoriasis. Comparison with serum interleukin-2 receptor levels.

Atopic dermatitis is associated with profound immunological alterations, in particular decreased lymphoproliferative responses upon stimulation with T-cell mitogens. T-cell blastogenesis involves the production of the soluble cytokine interleukin-2 (IL-2), which in turn upregulates the expression of its own receptor. To investigate the potential role of this cytokine for the pathomechanisms present in atopic dermatitis, 24-h supernatants of PHA-stimulated peripheral blood mononuclear cells from patients with atopic dermatitis (n = 30) of a moderate to severe disease activity were tested for IL-2 activity. In addition, serum concentrations of soluble interleukin-2 receptor (IL-2R) were measured. Non-atopic healthy controls (n = 19) and patients with psoriasis (n = 20), an inflammatory skin disorder with distinct pathogenesis, served as controls. In comparison with psoriasis patients and normal controls, PHA-stimulated mononuclear cells of atopic dermatitis patients released significantly less IL-2 into supernatants. Moreover, there was an inverse correlation between IL-2 concentrations and body surface involvement or serum IgE levels. In contrast, serum IL-2R levels were significantly elevated in both atopic dermatitis and psoriasis, as compared with healthy controls. Furthermore, IL-2R levels in atopic dermatitis patients showed a significant correlation with IgE levels and body surface involvement. The data indicate that T cell activation may occur in both skin diseases. Atopic dermatitis, however, is further characterized by the decreased capacity of mononuclear cells to release IL-2 upon stimulation in vitro.

Adolescent↗

PubMed1990

Enhanced endogenous leukotriene biosynthesis in patients treated with granulocyte-macrophage colony-stimulating factor.

The hematopoietic cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) is being used in clinical trials for its potential in the treatment of hematopoietic insufficiency due to various causes. Involvement of leukotrienes in the effects of GM-CSF is suggested by analytical and pharmacologic evidence obtained in vitro. However, until now no data in support of a role of leukotrienes in GM-CSF action in vivo have been presented. In the present investigation this question was approached by measurement of endogenous cysteinyl leukotriene formation in patients treated with the cytokine for cytopenia induced by cytostatic drugs or for refractory anemia with excess of blasts (RAEB). Endogenous cysteinyl leukotriene formation was assessed by determination of urinary leukotriene metabolites using combined high-performance liquid chromatography and radioimmunoassay analysis. After GM-CSF administration a distinct increase in urinary cysteinyl leukotrienes was found in the cytopenic and the RAEB patients that ranged from 2.3- to 57-fold and 2.4- to 333-fold, respectively. In the cytopenic patients the increase in leukotriene production was correlated to an expansion of peripheral blood leukocytes; RAEB patients responded to GM-CSF with enhanced leukotriene biosynthesis even if the peripheral leukocytes decreased, possibly due to an abnormal number and/or irritability of leukotriene-producing cells. The increase in endogenous leukotriene production during therapy with GM-CSF may indicate that leukotrienes play a role in GM-CSF action in vivo.

Adolescent↗

PubMed1990

Elevated levels of soluble CD8 antigen in sera of patients with psoriasis--a possible sign of suppressor/cytotoxic T-cell activation.

Increased levels of the soluble CD8 antigen probably represent a sign of suppressor T-cell activity. The concentration of CD8 was measured in the sera of patients with psoriasis without psoriatic arthritis (n = 25) and atopic dermatitis (n = 26), exhibiting moderate to severe disease activity, in comparison with nonatopic healthy controls (n = 31) using an ELISA technique. CD8 levels were found to be significantly elevated in psoriatic patients as compared with healthy controls (p less than or equal to 0.002). Increase in CD8 may be due to suppressor T-cell activation in the skin of patients with psoriasis.

Adolescent↗

PubMed1990

Interaction of granulocytes and endothelial cells upon stimulation with tumor necrosis factor-alpha: an ultrastructural study.

By the production of microbicidal agents, such as reactive oxygen species, activated PMN are capable of inducing tissue damage in the host. TNF-alpha was recently shown to be a potent activator of PMN oxidative metabolism. To further evaluate the interaction between activated PMN with physiological target cells, the effect of human PMN on cultured bovine aortic and human umbilical vein endothelial cells (EC) upon stimulation with human TNF-alpha was investigated by ultrastructural techniques: Scanning and transmission electron microscopy (SEM and TEM resp.) and ultrastructural detection of H2O2 production. When isolated PMN were added to EC in the presence of recombinant human TNF-alpha (10(3) U/ml) the EC-monolayer was disrupted within 4 h and EC changed their shape by exhibiting a spindle-like structure. PMN were seen in the intercellular spaces. Release of H2O2 was observed at the surface of the PMN plasma membrane, the luminal part of the small intracytoplasmic vacuoles in the PMN as well as in the contact zone between PMN and EC, but not within the EC. Scavengers of reactive oxygen species, such as superoxide dismutase and catalase or D-mannitol failed to block the effect of TNF-alpha-stimulated PMN on EC. In contrast, addition of NaN3 (0.1 mM), an inhibitor of myeloperoxidase activity, almost completely inhibited the disruption of EC-monolayers. Subsequent addition of NaN3-insensitive horseradish peroxidase reconstituted the effect. The results obtained suggest that TNF-alpha-stimulated PMN effectively cause the disruption of EC monolayers by an adherence-dependent mechanism which is mediated by the release of myeloperoxidase. The results may be of major importance for the pathogenesis of inflammatory vascular reactions.

Animals↗

PubMed1990

Tumor necrosis factor beta and ultraviolet radiation are potent regulators of human keratinocyte ICAM-1 expression.

Intercellular adhesion molecule-1 (ICAM-1) functions as a ligand of leukocyte function-associated antigen-1 (LFA-1), as well as a receptor for human picorna virus, and its regulation thus affects various immunologic and inflammatory reactions. The weak, constitutive ICAM-1 expression on human keratinocytes (KC) can be up-regulated by cytokines such as interferon-gamma (IFN gamma) and tumor necrosis factor alpha (TNF alpha). In order to further examine the regulation of KC ICAM-1 expression, normal human KC or epidermoid carcinoma cells (KB) were incubated with different cytokines and/or exposed to ultraviolet (UV) radiation. Subsequently, ICAM-1 expression was monitored cytofluorometrically using a monoclonal anti-ICAM-1 antibody. Stimulation of cells with recombinant human (rh) interleukin (IL) 1 alpha, rhIL-4, rhIL-5, rhIL-6, rh granulocyte/macrophage colony-stimulating factor (GM-CSF), rh interferon alpha (rhIFN alpha), and rh transforming growth factor beta (TGF beta) did not increase ICAM-1 surface expression. In contrast, rhTNF beta significantly up-regulated ICAM-1 expression in a time- and dose-dependent manner. Moreover, the combination of rhTNF beta with rhIFN gamma increased the percentage of ICAM-1-positive KC synergistically. This stimulatory effect of rhTNF beta was further confirmed by the demonstration that rhTNF beta was capable of markedly enhancing ICAM-1 mRNA expression in KC. Finally, exposure of KC in vitro to sublethal doses of UV radiation (0-100 J/m2) prior to cytokine (rhIFN tau, rhTNF alpha, rhTNF beta) stimulation inhibited ICAM-1 up-regulation in a dose-dependent fashion. These studies identify TNF beta and UV light as potent regulators of KC ICAM-1 expression, which may influence both attachment and detachment of leukocytes and possibly viruses to KC.

Biological Factors↗

PubMed1990

Activation of the oxidative metabolism in human polymorphonuclear neutrophilic granulocytes: the role of immuno-modulating cytokines.

Activated polymorphonuclear neutrophilic granulocytes (PMN) play an important role in propagation of inflammatory reactions and are capable of mediating tissue damage particularly by release of reactive oxygen species and lysosomal contents. Cytokines produced by monocytes as well as epidermal cells were recently shown to modulate PMN function. Therefore, the effect of immunomodulating cytokines on the oxidative metabolism of isolated human PMN was tested by functional as well as ultrastructural criteria. The following recombinant human cytokines were tested: tumor necrosis factor (TNF alpha), lymphotoxin (TNF beta), granulocyte-macrophage colony-stimulating factor (GM-CSF), M-CSF, G-CSF, PDGF, TGF-beta, interleukin-1 (IL-1) alpha and beta, IL-2, IL-3, IL-4, IL-5, IL-6, MONAP/MOC/NAF (IL-8), interferon-alpha and -gamma. Only TNF alpha, TNF beta and GM-CSF were found to be direct stimuli of the oxidative burst in human PMN whereas IL-3, IL-5, and IL-8 were active only at extremely high concentrations. None of the other cytokines tested induced any significant effect on isolated human PMN at physiological concentrations. The results clearly demonstrate that only selected cytokines are capable of inducing a long lasting activation of PMN oxidative metabolism. Release of these mediators represents a specific signal for PMN activation in inflammatory disease states.

Cytokines↗

PubMed1990

Immunomodulating cytokines in atopic dermatitis and psoriasis: production of tumour necrosis factor and lymphotoxin by mononuclear cells in vitro.

The immunomodulating cytokines, tumour necrosis factor/cachectin (TNF) and lymphotoxin (LT) are thought to play an essential role as mediators of inflammatory reactions. To evaluate the role of TNF and LT in atopic dermatitis (AD) and psoriasis, we investigated their production by mononuclear cells (MNC) in vitro. The 24-h supernatants of lipopolysaccharide (LPS)- and phytohaemagglutinin (PHA)-stimulated and unstimulated MNC from 26 patients with AD and 20 with psoriasis and from 17 non-atopic healthy controls were tested for the concentrations of TNF and LT using an ELISA technique. In patients with AD, TNF levels were significantly decreased in the supernatant of PHA-stimulated (P less than or equal to 0.005) and LPS-stimulated (P less than or equal to 0.02) MNC in comparison to controls. There was no significant difference in TNF production between psoriatic patients and the control group. Release of LT in the supernatant of PHA-stimulated MNC by patients and controls did not differ significantly. There was no significant spontaneous production of TNF and LT by MNC of patients and controls. These studies indicate that different immunomodulating mechanisms are responsible for triggering the inflammatory response in AD and psoriasis.

Adolescent↗

PubMed1990

[Activated granulocytes as producers of reactive oxygen species--their significance for inflammatory reaction].

The release of reactive oxygen species (ROS) by activated granulocytes is essential for the destruction of microbes and parasites in humans. Therefore, granulocytes play an important role in the pathogenesis of inflammatory reactions, particularly in inflammatory skin diseases. Besides their well-known toxic effects, ROS are capable of modulating a variety of different immune functions. The present review, therefore, focuses on the biological effects of ROS, on other producer cells of ROS besides granulocytes, on biochemical aspects of the production and interactions of ROS and on methods of detecting ROS production. Apart from well-known stimuli, which may be devoid of any physiological relevance or only induce a short-lived activation of granulocytes, cytokines are reported to induce a release of ROS. A possible modulatory effect of cytokines derived from immunocompetent and other cells on granulocyte activity could be of major importance for our understanding of the cellular interactions during inflammatory reactions, particularly in diseases characterized by granulocyte activation. The data presented allow a better understanding of the complex regulatory process of granulocyte activation in inflammatory skin diseases.

Biological Factors↗

PubMed1990

[Postherpetic erythema exsudativum multiforme with concomitant exacerbation of psoriasis vulgaris].

Herpes simplex virus (HSV) infection is a well-known trigger mechanism for both erythema multiforme (EM) and psoriasis. While HSV-related EM and psoriasis are not uncommon, simultaneous development of both disorders following HSV infection is relatively rare. We report on a patient who simultaneously developed both EM and a guttate psoriasis within 16 days of an HSV infection. The major differences in the pathophysiological mechanisms by which these dermatoses are triggered are discussed.

Biopsy↗

PubMed1989

Activation of human polymorphonuclear neutrophilic granulocytes by immuno-modulating cytokines: an ultrastructural study.

Activated granulocytes play an important role in the propagation of inflammatory reactions and are capable of mediating tissue damage by the release of reactive oxygen species and lysosomal contents. Cytokines produced by immunocompetent and other cells were recently suggested to influence granulocyte functions. Therefore, in the present study, we investigated the effect of relevant immuno-modulating cytokines on isolated human granulocytes by ultrastructural criteria: scanning and transmission electron microscopy, ultrastructural detection of H2O2. The following recombinant human cytokines were tested: tumor necrosis factor (TNF), lymphotoxin (LT), GM-CSF, M-CSF, G-CSF, interleukin 1 (IL 1) alpha and beta, IL 2, IL 3, IL 4, IL 6, interferon (IFN)-alpha and gamma. Only TNF, LT, GM-CSF and IL 3 (at high concentrations) induced significant morphological changes (increased adherence to plastic layers, typical polarization, development of intracellular vesicles) and production of H2O2. None of the other cytokines tested induced any detectable effect on isolated granulocytes even at unphysiological concentrations. The results clearly demonstrate that only certain cytokines are capable of influencing granulocytes. Release of these mediators represents a specific signal for granulocyte activation in inflammatory disease states.

Biological Factors↗

PubMed1989

Human tumor necrosis factor is a potent activator of the oxidative metabolism in human polymorphonuclear neutrophilic granulocytes: comparison with human lymphotoxin.

Besides their cytotoxic effects, Tumor necrosis factor (TNF) and Lymphotoxin (LT) were shown to modulate distinct PMN functions. Therefore, in the present study we evaluated the effect of recombinant human TNF and LT on the oxidative metabolism of isolated human PMN. In addition ultrastructural changes upon stimulation were evaluated. For detection of granulocyte activation different assay systems were used: 1) lucigenin-dependent chemiluminescence (CL), 2) superoxide-dismutase (SOD) inhibitable cytochrome C-reduction (superoxide), 3) horseradish peroxidase-mediated oxidation of phenol red (hydrogen peroxide), 4) release of myeloperoxidase, 5) ultrastructural detection of hydrogen peroxide-production, 6) scanning and transmission electron microscopy (SEM and TEM). TNF at concentrations as low as 10(-3) U/ml induced a distinct CL response, whereas LT appeared to be less active. PMN preincubated with TNF or LT for 150 min were completely deactivated to renewed stimulation with TNF, LT, and with GM-CSF, but responded to other triggers of the oxidative burst. Moreover, stimulation with f-met-leu-phe resulted in an enhanced response after preincubation with TNF or LT. The CL response was significantly inhibited by SOD, but not by catalase, D-mannitol, and DMTU, suggesting that mainly .O2- is responsible for the CL signal. The effect on PMN could be completely blocked by antibodies to TNF. Significant release of reactive oxygen species upon stimulation with TNF was also demonstrated by cytochrome C reduction and by detection of H2O2 using functional and ultrastructural assays. Only minimal amounts of peroxidase were released. Activation of PMN could be visualized by SEM and TEM. After addition of TNF at concentrations as low as 10(-1) U/ml PMN adhered to the substratum and were typically polarized within 15 min. Stimulation with LT resulted in comparable results, but based on its biologic activity in the cytotoxicity assay LT, in comparison to TNF, was significantly less active. Based on the data presented LT and, particularly, TNF appear to be potent activators of PMN oxidative metabolism.

Humans↗