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Biomedical subjects

C Dahlgren

Publications and source records attributed to C Dahlgren.

At least 109 records · Page 6Linked to original sources
PubMed1988

Function of exudate neutrophils from skin in psoriasis.

Human neutrophils harvested from skin chambers containing autologous serum in psoriatic patients were compared with peripheral blood neutrophils by examining migration, phagocytosis, and oxidative activation. Random migration was reduced in exudate cells, whereas the chemotactic response to yeast-activated serum was evident not only in blood neutrophils, but also in exudate cells. The metabolic activation of exudate neutrophils, when stimulated with formyl-methionyl-leucyl-phenylalanine and measured as chemiluminescence, was enhanced by 50-400% compared to blood neutrophils. The chemiluminescence response to phorbol myristate acetate was on the other hand reduced to 35%. In the phagocytic assay, using C3bi- and IgG-opsonized yeast particles, exudate neutrophils from non-psoriatic healthy controls showed enhanced uptake of C3bi-coated yeast compared to blood neutrophils. In psoriatics, the blood neutrophils showed enhanced C3bi-mediated phagocytosis compared to non-psoriatic control cells. No further increase in C3bi-mediated phagocytosis was then seen in exudate cells from these patients. IgG-mediated phagocytosis was in contrast to C3bi similar between blood and exudate neutrophils in psoriatics and non-psoriatic controls. These experiments show that during exudation priming of different receptor-mediated processes can occur. However, no significant difference was observed between different functional capacities in exudate neutrophils from psoriasis patients and non-psoriatic controls.

Adult↗
PubMed1988

The limitation of the human neutrophil chemiluminescence response by extracellular peroxidase is stimulus dependent: effect of added horse radish peroxidase on the response induced by both soluble and particulate stimuli.

When polymorphonuclear leukocytes (PMNL) interact with soluble and particulate stimuli, the cells increase their production of oxidative metabolites. This increased production can be measured as luminol amplified light emission or chemiluminescence (CL). The CL response of human PMNL has been investigated, and it was found that the formyl-methionyl-leucyl-phenylalanine (FMLP) and the phorbol myristate acetate (PMA) induced responses were limited by the amount of available peroxidase, whereas the ionomycin induced response was unaffected by the amount of extracellular peroxidase. A small increase in the response induced by the Salmonella typhimurium MR10 bacteria upon addition of peroxidase was also observed. The results indicate that stimuli inducing an intracellular response in PMNL are insensitive to the amount of extracellularly released peroxidase, whereas the response induced by stimuli also generating an extracellularly located production of oxidative metabolites are highly influenced by the amount of peroxidase available extracellularly. Furthermore, the extracellularly localized peroxidase dependency is reduced at higher luminol concentrations. The use of the luminol-amplified chemiluminescence technique in various types of scientific investigations is discussed.

Adult↗
PubMed1988

Characteristics of the granulocyte chemiluminescence reaction following an interaction between human neutrophils and Salmonella typhimurium bacteria.

The production of reactive oxygen metabolites by neutrophils is thought to play a key role in the host defence against invading microorganisms. The production of these oxidative metabolites can be measured as chemiluminescence. In this study, two strains of Salmonella typhimurium were used as stimuli, and the opsonin-independent CL response from neutrophils challenged with these bacteria was investigated. The strains used, S. typhimurium 395 MS and a rough (Rd Epi-2) mutant 395 MR10, differ with respect to physicochemical surface characteristics. When neutrophils were exposed to the phagocytic prey, only the MR10 bacteria induced a CL response. The response induced by the MS bacteria was less than 2% of that induced by MR10. In order to study the relation between intra and extracellularly generated CL, systems were used which selectively inhibit the intra and extracellular CL, respectively. Using these systems it was found that a predominant part of the response was of intracellular origin. When the neutrophils were treated with cytochalasin B (5 micrograms) before the addition of the bacteria, the CL response was reduced to around 37% of the value obtained from untreated cells, and the relation between the extra and the intracellular parts of the response was changed. The mechanism(s) and biological consequences of the extracellular and intracellular generation of oxygen metabolites, respectively, are discussed.

Cytochalasin B↗
PubMed1987

Difference in extracellular radical release after chemotactic factor and calcium ionophore activation of the oxygen radical-generating system in human neutrophils.

Results obtained with the luminol-dependent chemiluminescence technique show that with this technique, generation of radicals from an extra- as well as from an intracellular source is quantified. By means of a chemiluminescence technique, using human neutrophils stimulated with the chemoattractant formylmethionylleucylphenylalanine and the calcium ionophore ionomycin, two different mechanisms of radical production and release are demonstrated. The chemoattractant causes the cells to produce oxygen radicals which to a large extent are released from the cells. The calcium ionophore is also capable of stimulating radical formation but does not suffice for extracellular release. Furthermore, the removal of extracellular Ca2+ is of minor importance for the extracellular radical production, whereas it totally inhibits the generation of radicals with an intracellular localization. The mechanism(s) behind intracellular and extracellular production of oxygen radicals is discussed.

Adult↗
PubMed1987

Chemotactic factor binding and functional capacity: a comparison between human granulocytes and differentiated HL-60 cells.

In the presence of dimethyl sulfoxide (DMSO), the leukemic promyelocytic cell line HL-60 will differentiate into mature polymorphonuclear granulocytes. In the present report, we compare chemotactic factor binding and function in HL-60 cells with that of normal human granulocytes using the chemotactic peptide N-formylmethionyl-leucyl-phenylalanine (FMLP) as ligand. The cellular response measured as CL was changed as a result of storage or conditioning of normal peripheral blood cells. With these cells, a conditioning procedure at room temperature resulted in a pronounced increase in the CL response. The increase of the CL response was probably a result of increased expression of cryptic receptors, since the changes of the oxidative response to FMLP was accompanied by increased binding of the peptide to the cell surface. Scatchard analysis revealed that the increased binding was due to an increased number of receptors. In differentiated HL-60 cells, conditioning neither led to increased production of oxidative metabolites, nor to any increased binding of the peptide. The data thus indicate that many FMLP receptors could reside in a cryptic site that is not accessible to extracellular ligands, and that conditioning results in an increased exposure of these receptors, followed by an increased oxidative response to the ligand in normal cells but not in mature HL-60 cells.

Cell Line↗
PubMed1987

Polymorphonuclear leukocyte chemiluminescence induced by formylmethionyl-leucyl-phenylalanine and phorbol myristate acetate: effects of catalase and superoxide dismutase.

When polymorphonuclear leukocytes (PMNL) interact with the soluble stimuli FMLP or PMA, the cells increase their production of oxidative metabolites. This increased production can be measured as luminol amplified light emission or chemiluminescence (CL). The chemiluminescence of human PMNL has been investigated, and it was found that the chemoattractant FMLP induced a bimodal response with a sharp peak of activity within 1 min, and a second peak after around 5 min. In contrast, PMA induced a one peak response reaching a maximum around 15 min after stimulis addition. Despite the fact that strictly standarized conditions for cell preparation and CL measurements were used, an extensive variability, especially in the response to FMLP was observed. Dismutation of O(2) by the addition of superoxide dismutase (SOD) or consumption of H2O2 by addition of catalase resulted in very small reductions of the CL compared to the effects on cytochrome c reduction and scopoletine fluorescence, respectively. Furthermore, since SOD reduced also the CL generated from a cell-free peroxide-peroxidase system, the specificity of SOD in the CL reaction could be questioned. Expression of CL and the effects of SOD and catalase was furthermore found to be dependent on the number of responding cells. Analysis of the effects of SOD and catalase on the bimodal FMLP response show that the first peak is strongly inhibited, whereas a very small effect upon the expression of the second peak is obtained. These results indicate, that since SOD and catalase are expected to reduce only extracellularly generated oxidative metabolites, the first peak of the FMLP response is of extracellular origin, whereas the second peak and most of the PMA induced response are cell associated or intracellular phenomena.

Adult↗
PubMed1987

The adherence of polymorphonuclear leucocytes to an albumin-coated glass surface. Effects of therapeutic concentrations of the Catharantus derivatives vincristine, vinblastine and vindesine.

The Catharantus derivatives are microtubule antagonists employed in immunosuppression and chemotherapy of neoplasms. The role of cytoplasmic microtubules in polymorphonuclear leucocyte (PMN) adherence was studied by means of therapeutic concentrations of the Catharantus derivatives vincristine, vinblastine and vindesine. PMN adherence was measured as retention on an albumin-coated glass surface. PMN adherence was reduced by 4-54% by the Catharantus derivatives, as compared with control values. The suppression of adherence was statistically significant. Since the Catharantus derivatives are microtubule antagonists, it is reasonable to assume that PMN adherence is a partially microtubule-dependent process. It is suggested that reduction of PMN adherence could account for at least part of the immunosuppressive properties of the Catharantus derivatives.

Cell Adhesion↗
PubMed1987

Influence of antibiotics on formylmethionyl-leucyl-phenylalanine-induced leukocyte chemiluminescence.

The effect of three antimicrobial agents, penicillin G, ampicillin, and chloramphenicol, on luminol-enhanced chemiluminescence of polymorphonuclear leukocytes stimulated by the chemoattractant formylmethionyl-leucyl-phenylalanine was studied. An inhibitory effect of penicillin G and of ampicillin was demonstrated, whereas chloramphenicol gave rise to an enhancement of the chemiluminescence response from polymorphonuclear leukocytes. These effects could be due to interaction between the drugs and the polymorphonuclear leukocytes, but they could also be the result of interference with the generation of light without any effect on the cells. Therefore, the effects of the same antimicrobial agents on the chemiluminescence generated from a cell-free system consisting of myeloperoxidase and hydrogen peroxide were investigated in parallel. The results obtained in the cell-free system were almost identical to those obtained in the cell system; i.e., penicillin G and ampicillin caused an inhibition and chloramphenicol caused an enhancement of the light emission. These results indicate that observed effects induced by drugs in a chemiluminescence assay are not necessarily due to interaction between the drug and polymorphonuclear leukocytes but may be caused by interference with other components of the assay. In view of these findings, the conflicting data reported in the literature on the effects of antimicrobial agents on phagocyte function are discussed.

Ampicillin↗
PubMed1987

Cell surface expression of fMet-Leu-Phe receptors on human neutrophils. Correlation to changes in the cytosolic free Ca2+ level and action of phorbol myristate acetate.

We have studied how cytosolic free Ca2+ ([Ca2+]i) changes and phorbol myristate acetate (PMA) exposure affects ligand-independent cell surface expression of fMet-Leu-Phe receptors on human neutrophils. Mere incubation primed neutrophils to double their binding of fMet-Leu-Phe. This spontaneous increase of peptide binding was unaffected by changes in the extracellular calcium concentration. However, depression of the [Ca2+]i totally abolished the increased binding of fMet-Leu-Phe. Scatchard-Plot analysis revealed that the observed increase of peptide binding was due to an increased number of receptors. Normalization of the [Ca2+]i in cells where it was initially depressed resulted in a slow but progressive increase in fMet-Leu-Phe binding. The rate of receptor recruitment could be enhanced by rapidly increasing the [Ca2+]i by addition of ionomycin. Addition of PMA to cells with near maximal receptor expression led to a marked reduction of fMet-Leu-Phe binding without affecting [Ca2+]i. These observations suggest the existence of a dual regulatory mechanism for up- and down-regulation of fMet-Leu-Phe receptors on the cell surface of human neutrophils.

Aminoquinolines↗
PubMed1987

Doxycycline effects on the adherence of polymorphonuclear leukocytes to an albumin-coated glass surface.

The effect of doxycycline on polymorphonuclear leukocyte (PMN) adherence to albumin-coated glass surfaces was studied in the absence and presence of the chemotactic peptide FMLP. Three concentrations of doxycycline were studied, one subtherapeutic (0.1 micrograms/ml), one therapeutic (1.0 micrograms/ml) and one supertherapeutic (10 micrograms/ml). PMN adherence was maximal after incubation for 5 min. FMLP did not affect PMN adherence in the present assay system and at the concentration studied (10(-7)M). PMN adherence remained stable and unaffected in the tested doxycycline concentrations. Thus, the present study could not confirm the reported and challenged doxycycline inhibition of PMN adherence.

Albumins↗
PubMed1987

Neutrophil function in psoriasis: effects of retinoids.

The present investigation focused on the oxidative response of polymorphonuclear neutrophil leukocytes in psoriasis, in particular pustular psoriasis and how this response was affected by different retinoid compounds. In the active phase of pustular psoriasis, the neutrophil chemiluminescence response to the chemotactic peptide f-met-leu-phe and to phorbol myristate acetate was enhanced and correlated to the development of pustules, whereas cells from psoriasis vulgaris patients showed normal chemiluminescence response. Retinoids, particularly tretinoin (= retinoic acid) and isotretinoin caused a pronounced inhibition of the chemiluminescence response only in primed neutrophils in vivo and in vitro, whereas etretinate and the metabolite Ro 10-1670 was less inhibitory. Retinoic acid furthermore inhibited the Fc-mediated phagocytosis, but did not affect C3bi-mediated phagocytosis. These data suggest that the antiinflammatory effect of retinoids may operate by affecting neutrophil activation and function.

Acitretin↗
PubMed1986

Defective chemiluminescence response in differentiated HL60 cells due to impaired degranulation.

In the presence of dimethyl sulfoxide, the promyelocytic leukemic cell line, HL60, differentiates into apparently mature polymorphonuclear leukocytes. When correlating the superoxide production from HL60 cells with the number of phagocytozing and NBT-positive cells, no difference was observed in comparison with normal peripheral blood leukocytes. In contrast, the luminol-dependent chemiluminescence was greatly impaired in the differentiated HL60 cells. Analysis of degranulation, i.e., release of myeloperoxidase and N-acetyl-beta-glucosaminidase- and myeloperoxidase-mediated iodination by HL60 cells, suggested that the defective chemiluminescence response observed in HL60 cells may be due to impaired release of myeloperoxidase from azurophilic granulae. This may lead to impaired microbicidal activity in these cells.

Cell Differentiation↗
PubMed1986

Superoxide production and chemiluminescence induced in differentiated HL-60 cells by the chemoattractant formyl-methionyl-leucyl-phenylalanine.

Superoxide production and chemiluminescence induced in differentiated HL-60 cells by the chemoattractant formylmethionyl-leucyl-phenylalanine: In order to study the generation of oxidative metabolites in relation to cell differentiation, dimethyl sulfoxide (DMSO) and retinoic acid (RA) differentiated HL-60 cells were stimulated with the chemotactic peptide formylmethionyl-leucyl-phenylalanine (FMLP). The oxidative response was measured as luminol-dependent chemiluminescence, lucigenin-dependent chemiluminescence, and cytochrome c reduction. Cells grown in the presence of DMSO or RA progressively expressed morphological changes, and when the mature cells were exposed to FMLP the cells produced oxidative metabolites. Quantitatively the HL-60 cells grown in the presence of DMSO gave rise to the most pronounced response. No correlation was obtained between superoxide production, luminol-chemiluminescence and lucigenin-dependent chemiluminescence, indicating that different aspects of the oxidative response are elucidated by the three different methods. Furthermore, the experiments show that DMSO and RA-induced differentiation of HL-60 cells leads to granulocyte-like cells with different abilities to produce oxidative metabolites, possibly due to differences in receptor function.

Cell Differentiation↗
PubMed1986

Factor-specific deactivation of leucocyte chemotaxis in vivo.

This report analyses the locomotory capacity of polymorphonuclear leucocytes (PMNL) isolated from 7 patients with bacterial meningitis. 7 healthy control subjects were also investigated in parallel. It was found that PMNL from the patients suffering from meningitis, isolated both from peripheral blood and from the cerebrospinal fluid, had lost their ability to respond chemotactically to activated serum but not to the chemotactic peptide f-Met-Leu-Phe. The normal chemotactic responsiveness of blood PMNL was restored once the patients recovered from infection.

Blood Physiological Phenomena↗
PubMed1986

Characterization of fMet-Leu-Phe receptor-mediated Ca2+ influx across the plasma membrane of human neutrophils.

N-Formyl-L-methionyl-L-leucyl-L-phenylalanine (fMet-Leu-Phe) stimulation of human neutrophils leads to a rapid increase of the cytosolic free Ca2+ concentration, [Ca2+]i, which is significantly reduced by removal of extracellular calcium. In the present study we show that fMet-Leu-Phe-induced [Ca2+]i increases are, in part, mediated by an increase of the plasma membrane permeability to Ca2+. This conclusion is based on the following evidence. In the presence of extracellular calcium, addition of La3+ reduced the fMet-Leu-Phe-induced [Ca2+]i increase to approximately the same level as that observed in the absence of extracellular calcium. A net increase of the plasma membrane permeability for Mn2+ could be observed after fMet-Leu-Phe stimulation, as revealed by intracellular quenching of the quin2 signal. The influx of Mn2+, like that of Ca2+, was inhibited by La3+ and was more pronounced in the absence of extracellular Ca2+, suggesting competition for the same pathway. Temporal dissociation of intracellular Ca2+ release from stores and Ca2+ influx from the medium could be demonstrated by readdition of calcium to cells stimulated in the absence of this cation. This second [Ca2+]i increase could be abolished either by giving the specific chemotactic peptide receptor antagonist, BOC-Met-Leu-Phe, or Co2+. We could also show that the fMet-Leu-Phe-dependent Ca2+ influx was not due to the activation of voltage-dependent calcium channels since depolarization either by K+ or gramicidin D did not affect the resting [Ca2+]i, nor did it affect a subsequent [Ca2+]i increase induced by fMet-Leu-Phe. Furthermore, nifedipine and verapamil, at concentrations known to block classical voltage-dependent calcium channels, had no significant effects on the Ca2+ influx induced by fMet-Leu-Phe. We suggest that fMet-Leu-Phe promotes influx of Ca2+ ions across the plasma membrane of human neutrophils by opening of receptor-dependent calcium channels.

Adult↗
PubMed1985

Influence of fluid-phase chemoattractants on polymorphonuclear leukocyte chemotaxic responsiveness to a surface-bound attractant.

Polymorphonuclear leukocytes (PMNLs) were allowed to migrate on slides with fixed yeast particles dotted about on the surface. Locomotion was quantified by counting the number of yeast particles in association with a PMNL. Addition of a complement source to yeast particles able to activate the complement system resulted in a chemotactic response even when fluid-phase attractants were removed prior to the measurement of PMNL chemotaxis, indicating that surface-bound attractants guided the PMNLs to the yeast particles. The presence of high concentrations of fluid-phase chemoattractants resulted in a reduced PMNL chemotactic response to the surface-bound gradient. From comparisons between the yeast-slide system and the locomotion-under-agarose assay, it could be concluded that PMNL chemotaxis in response to a surface-bound gradient is less influenced by factor-specific deactivation than the response to a fluid-phase attractant. The PMNL chemotactic response is reduced to both surface-bound and fluid-phase gradients as a result of a non-factor-specific deactivation.

Cell Movement↗