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Biomedical subjects

C Dahlgren

Publications and source records attributed to C Dahlgren.

At least 127 records · Page 7Linked to original sources
PubMed1985

Effect of N-formylated methionyl-phenylalanine (FMP) and methionyl-leucyl-phenylalanine (FMLP) on gut permeability. A model of local inflammatory process.

With the aim of elucidating inflammatory reactions in intestinal mucosa evoked by agents of microbial origin, the effect was assessed on intestinal permeability in the rat of two known chemoattractants for granulocytes and macrophages, N-formyl-methionyl-phenylalanine (FMP) and N-formyl-methionyl-leucyl-phenylalanine (FMLP). Fluoresceinated dextran (mol wt 3000 daltons) was used as a permeability marker. It was found that increasing concentrations of FMP enhanced the transmural passage up to a maximum at 2 X 10(-7)-2 X 10(-6)M. With FMLP the effect was greater than with FMP and measurable at 2 X 10(-9)-2 X 10(-8)M. The increased permeability was apparent 1-5 min after introduction of the peptides and prevailed during the 45-min measuring period. The bimodal response to the peptides is discussed in relation to different potential target-effector cells in the intestinal wall.

Animals↗
PubMed1985

Inhibition of human leukocyte metabolism and random mobility by local anaesthesia.

Hexose-monophosphate shunt (HMS) activity, myelo-peroxidase-(MPO)-mediated iodination and random mobility in human polymorphonuclear leukocytes (PMNs) were studied in the presence of lignocaine. Incubating the PMNs with 0.1% lignocaine during phagocytosis inhibited the 14CO2 produced from glucose-1-14-C via the HMS shunt by 33%. On increasing the concentration of lignocaine, a dose-dependent inhibition was noted. The MPO-mediated iodination was inhibited by 73% in the presence of 0.1% lignocaine, and complete inhibition took place when the concentration was increased to 0.5%. The random mobility of leukocytes was studied by an opto-electronic technique. In the presence of 0.5% lignocaine, all leukocytes examined were completely immobilized; in the presence of 0.1% lignocaine immobilization took place within 45-65 min.

Anesthetics, Local↗
PubMed1985

Pattern of formylmethionyl-leucyl-phenylalanine-induced luminol- and lucigenin-dependent chemiluminescence in human neutrophils.

The stimulation of neutrophils by formylmethionyl-leucyl-phenylalanine results in a bimodal luminol-dependent chemiluminescence pattern. We observed, however, only a single peak chemiluminescence pattern in the response to the peptide when we used lucigenin as an amplifying substance. We suggest that lucigenin, the larger molecule, (510 daltons; luminol is 177 daltons) only exerts an extracellular effect.

Acridines↗
PubMed1984

Myeloperoxidase reduces the opsonizing activity of immunoglobulin G and complement component C3b.

The effect of myeloperoxidase, hydrogen peroxide (H2O2) and a halide (Cl) on the opsonizing molecules in immunoglobulin G (IgG) and complement factor C3b was assayed. At concentrations of the enzyme (1 microgram/ml) that can be found in the extracellular fluid during inflammation, the myeloperoxidase-H2O2-Cl system inhibited the opsonizing effect of IgG and C3b measured as phagocytic uptake and superoxide generation. The effect was related to the enzymatic peroxidative activity of the protein. The presence of albumin (10 mg/ml) reduced the effect of myeloperoxidase with 10-20%. Taurine, which in the presence of myeloperoxidase-H2O2-Cl forms hydrophilic chloramines, and D-penicillamine, which scavenges HOCl, neutralize the inhibitory effect of myeloperoxidase. This suggests that either hypochlorous acid or lipophilic chloramines may exert its effect by oxidizing free sulphydryl groups exposed on the opsonizing ligands. Since the myeloperoxidase-H2O2-halide system also affects chemotactic factors, leukotrienes, proteinases and membrane receptors, the system may in several ways affect the development of the inflammatory response.

Complement C3b↗
PubMed1984

Concentration gradients in the under-agarose chemotaxis assay system with attractant surface adsorption.

To evaluate directional locomotion or chemotaxis of polymorphonuclear leukocytes (PMNL), assay conditions need to be understood quantitatively. The characteristics of the gradient of a chemoattractant in an assay system depend on, for example, the geometry of the system and the diffusion coefficient of the attractant, but since PMNL are able to respond to surface-bound attractants, surface adsorption of the attractant might also be a factor of importance. We have solved the diffusion equation to characterize the gradients present in the under-agarose assay system, when surface adsorption of the chemoattractant is taken into account. Application of the theory to experimental data shows that surface adsorption is important for the cellular response to the chemotactic factor generated from normal human serum, but not for the response to the chemotactic peptide fMLP.

Adsorption↗
PubMed1984

Complement factor adsorption on solid surfaces--an ellipsometric method for investigation of quantitative aspects.

An optical method, ellipsometry, has been used for quantification of organic material adsorbed from complement sufficient sera on antibody coated solid surfaces. Maximal adsorption of organic material from complement sufficient human sera occurred at about 0.5 micrograms/cm2 of IgG. C3 but not C5, C8 or C9 was detected on the antibody surface incubated with complement sufficient sera. This may indicate that IgG adsorbed on methylized silicon surfaces lack binding sites for complement factors beyond C3. A modification of the method was also used for quantification of migration inhibition of human polymorphonuclear leucocytes (PMNL). Locomotion inhibition fell in a sharp interval from 0.2 to 0.5 micrograms/cm2 of IgG on the surface. We believe that the suggested type of measurements is important for understanding the quantitative relationships between humoral effects such as antibody dependent complement activation and cellular effects such as migration of PMNL.

Adsorption↗
PubMed1984

Chemotaxis of polymorphonuclear leukocytes in response to surface-bound complement-derived chemoattractants generated in situ.

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. Yeast particles that differed in their ability to consume hemolytic complement differed also in their ability to generate chemoattractants. Addition of a complement source to yeast particles able to activate the complement system resulted in a chemotactic response, as well as when fluid-phase attractants were removed prior to the measurement of PMNL chemotaxis, indicating that the chemoattractants generated were absorbed to the surface. Using an immunofluorescence technique, it was found that complement factor 5 coated a circular area around each yeast particle, provided that the particles were able to activate the complement system.

Chemotactic Factors↗
PubMed1984

Comparison between luminol- and lucigenindependent chemiluminescence of polymorphonuclear leukocytes.

Phorbolmyristate acetate (PMA) induced both a luminol- and a lucigenindependent chemiluminescence response in normal polymorphonuclear leukocytes (PMNL). PMNL isolated from a patient with a myeloperoxidase (MPO)-deficiency were found to produce almost no luminol-dependent chemiluminescence. The lucigenin-dependent chemiluminescence response was, however, found not to differ between normal and MPO-deficient cells. From these results it was concluded that the luminol- and the lucigenin-dependent chemiluminescence differed in the dependence of MPO. Results obtained with cell-free MPO-H2O2- and superoxide anion producing systems further supported this conclusion.

Acridines↗
PubMed1984

Intra- and extracellular events in luminol-dependent chemiluminescence of polymorphonuclear leukocytes.

When polymorphonuclear leukocytes (PMNL) and soluble or particulate matter interact, the cells produce chemiluminescence. Luminol-dependent light emission from PMNL is linked to the myeloperoxidase (MPO)-H2O2 system. Light emission from a cell-free MPO-H2O2 system was found to be totally inhibited by human serum albumin (HSA), and since HSA is a large molecular protein that does not readily gain access to intracellular sites of PMNL, it could be used to determine the importance of extra- and intracellular events in PMNL chemiluminescence. In studies with cells from an MPO-deficient patient, we found that HSA inhibited more than 90% of extracellularly produced chemiluminescence. The chemotactic peptide formylmethionyl-leucyl-phenylalanine induced a two-peak chemiluminescence response in normal PMNL, and addition of HSA reduced the first peak, whereas the second peak was unaffected. This result indicated that the first peak was a result of extracellular reactions and the second peak was a result of intracellular reactions of the MPO-H2O2 system. Most of the phorbol myristate acetate-induced response in normal PMNL was due to intracellular events. Furthermore, chemiluminescence of intracellular origin seems to be limited not by generation of oxidative metabolites but by diffusion of luminol into the cells.

Humans↗
PubMed1984

Myeloperoxidase modulates the phagocytic activity of polymorphonuclear neutrophil leukocytes. Studies with cells from a myeloperoxidase-deficient patient.

Patients lacking the primary granulae enzyme, myeloperoxidase (MPO), do not usually show any increased susceptibility to infection or altered inflammatory response, in contrast to several other biochemical defects in polymorphonuclear neutrophils. We have now evaluated the role of MPO on phagocyte function in a patient with complete MPO deficiency suffering from generalized pustular psoriasis. We found that the MPO-deficient neutrophils showed enhanced phagocytosis (greater than 200% of normal) of IgG- and C3b-opsonized yeast particles and prolonged N-formylmethionyl-leucyl-phenylaline-mediated stimulation of superoxide production. When purified human MPO was added to normal neutrophils during cell adhesion, their Fc- and C3b-mediated phagocytosis was reduced without affecting cell viability. 1 microgram/ml of MPO reduced the Fc and C3b phagocytosis to 47 and 65%, respectively, whereas 10 micrograms/ml reduced the activity to 20 and 54%. Both attachment and ingestion were reduced to a similar extent, indicating that MPO affected the receptor function per se. When MPO was added to the hyperactive MPO-deficient cells, phagocytosis was reduced more rapidly. Catalase, azide, and methionine eliminated the inhibitory effect, and catalase and methionine, in fact, enhanced the phagocytic activity of adherent neutrophils. These data indicate that, apart from being a potent antimicrobial system, the oxidizing activity of the MPO-H2O2-halide system may modulate the inflammatory response by impairing certain receptor-mediated recognition mechanisms of phagocytic cells, which otherwise could elicit inflammatory reactions and tissue injury.

Complement C3b↗
PubMed1983

A quantitative microassay for leukocyte chemotaxis, using a microscopic slide system with complement-activating yeast particles as gradient source.

A simple quantitative microassay was developed for studying polymorphonuclear leukocyte (PMNL) chemotaxis under conditions where the number of available cells is a limiting factor, e.g., pustules, neutropenia, small children and cerebrospinal fluid. PMNL suspensions are placed on glass slides to which fluorescein-labeled yeast particles have been fixed. After adherence, normal human serum is added to the slides. Owing to complement activation, a chemotactic gradient which attracts the adherent PMNL is formed around the yeast particles. The number of PMNL-associated yeast particles in the presence of normal serum is scored, and compared with cells migrating in the presence of inactivated serum or in the absence of serum. A locomotory index is calculated as the number of yeast particles associated with PMNL divided by the total number of yeast particles.

Blood Physiological Phenomena↗
PubMed1983

A simple fluorescence technique to stain the plasma membrane of human neutrophils.

Three different fluorochromes were tested for their ability to label the plasma membrane proteins of neutrophils without labelling intracellular structures. A fluorescence quenching technique was used to differentiate between extra- and intracellularly localized fluorescence. Fluorescamin and fluoresceinisothiocyanate were shown to stain intracellular structures as well as the plasma membranes of the cells. Another fluorochrome, Evans Blue, is proposed since this dye was shown, by using the fluorescence quenching technique, to selectively stain the plasma membrane of viable neutrophils.

Cell Membrane↗
PubMed1983

Lateral diffusion of wheat germ agglutinin-labeled glycoconjugates in the membrane of differentiating HL-60 and U-937 cells assessed with fluorescence recovery after photobleaching (FRAP).

The promyelocytic leukemia cell line HL-60 and the histiocytic cell line U-937 were grown in suspension culture. They were induced to differentiate during 5-d cultivation in the presence of dimethylsulfoxide (DMSO; 1.3% w/v) or phorbol-12-myristate-acetate (PMA; 10(-7) M), which yields granulocyte- and macrophage-like cells, respectively. Differentiation was evidenced by increased capacity to recognize and phagocytize IgG- or complement-coated yeast particles. Aliquots taken from the cultures with and without DMSO (or PMA) were spun down directly on glass microscope slides, washed, labeled with fluoresceinated wheat germ agglutinin (WGA), and directly examined at room temperature for the rate of fluorescence recovery after photobleaching (FRAP). It was found that cultivation of the HL-60 and the U-937 cells in the presence of DMSO, which yields granulocyte-like cells, reduced the average value of lateral diffusion coefficient D (X 10(10] from 1.72 +/- 0.13 cm2s-1 to 0.97 +/- 0.13 cm2s-1 and from 1.77 +/- 0.11 cm2s-1 to 0.82 +/- 0.13 cm2s-1, respectively. U-937 cells grown with PMA also showed a reduction of D(X 10(10] to 0.88 +/- 0.10 cm2s-1. There was a larger immobile fraction of fluorescence in the HL-60 cells than in the U-937 cells, viz., 70-80% compared to 10-50%. The total number of binding sites for WGA was not altered, but the surface density changed, since the HL-60 and the U-937 cells became smaller and larger, respectively, when grown in the presence of DMSO. It is concluded that differentiation reduces the average lateral mobility of the WGA-binding membrane component by a factor around 2.

Cell Differentiation↗
PubMed1983

Role of myeloperoxidase in luminol-dependent chemiluminescence of polymorphonuclear leukocytes.

When polymorphonuclear leukocytes (PMNL) and soluble or particulate matter interact, the cells produce chemiluminescence, linked to activation of the oxidative metabolism of the cells. PMNL isolated from a patient with a myeloperoxidase deficiency were found to produce almost no luminol-dependent chemiluminescence, despite a pronounced production of superoxide anions (O2-). The chemotactic peptide formylmethionyl-leucyl-phenylalanine induced a two-peak chemiluminescence response in control PMNL. The response was modified, both in magnitude and in time-course, when the cells were incubated at 22 degrees C for 120 min. Addition of purified myeloperoxidase to the PMNL lacking this enzyme, before stimulus addition, resulted in a chemiluminescence response. In the response to formylmethionyl-leucyl-phenylalanine, only one peak, corresponding to the initial peak of control PMNL, was found. This indicated that luminol-dependent chemiluminescence is dependent on and directly related to the presence of myeloperoxidase in PMNL and that both intra- and extracellularly located myeloperoxidase has to be taken into account when interpreting the cellular response assayed as chemiluminescence.

Cytochalasin B↗
PubMed1983

Inhibition of polymorphonuclear leucocyte locomotion by surface-bound antigen-antibody complexes.

Locomotion of polymorphonuclear leucocytes (PMNL) on solid surfaces with bound antigen-antibody complexes was studied. The amount of surface-bound antibody was determined with ellipsometry, a surface-sensitive optical method. Locomotion of PMNL was inhibited on surfaces coated with bilayers of human serum albumin and the corresponding antibody. The critical amount of antibody required for inhibition was measured to 0.50 X 10(-8) micrograms/microns 2, corresponding to 1.6 X 10(6) antibody molecules per PMNL. Once immobilized on antigen-antibody coated surfaces, PMNL did not move chemotactically in response to formylmethionyl-leucyl-phenylalanine (fMLP). The receptor for fMLP appeared to be intact, however, since the cells responded metabolically to the chemotactic peptide.

Antigen-Antibody Complex↗
PubMed1982

Physicochemical and functional changes in human leukemic cell line HL-60.

The recently established human promyelocytic cell line HL-60 was induced to differentiate in the present of DMSO. During this process, physicochemical, and functional changes were detected simultaneously. After exposure to DMSO for more than 1 day, the cell volume decreased and the tendency for hydrophobic interaction increased. Using a hydrophobic two-phase system in counter current distribution fashion, it was then possible to separate more mature metamyelocytes and segmented granulocytes from immature myeloblasts and promyelocytes. Increased functional maturity was reflected by increased chemiluminescence (CL) response and phagocytic activity. Using yeast particles opsonized with IgG as stimulating agent, the CL response increased already after 1 day in DMSO, in parallel with increased phagocytosis of these particles. In contrast, C3b-opsonized yeast and phorbol 12-myristate 13-acetate (PMA) did not enhance the CL response conspicuosly until days 3-4. These data suggest that Fc receptor function linked to phagocytosis and the activation of oxidative metabolism develop earlier than that of C3b and PMA. The dissociation between Fc- and PMA-dependent stimulation of the oxidative metabolism may reflect different mechanisms of activation.

Cell Differentiation↗