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Acta Biologica Et Medica Germanica 1979The ability of insect blood cells to ingest all kinds of synthetic particles and also a wide range of microorganisms in a very short time after injection has up to now...
The ability of insect blood cells to ingest all kinds of synthetic particles and also a wide range of microorganisms in a very short time after injection has up to now been regarded as a phagocytic function without any humoral mediators. In a phagocytosis model with latex beads and nonhagocytosable cells of Bacillus thuringiensis subtoxicus, we are able to demonstrate the existence of lymphokine-like factors, which intervene in cellular defence reactions of insect. The following results were obtained: 1. Immediately after injection of latex beads, normally non-phagocytosable cells of Bacillus thuringiensis subtoxicus are phagocytosed. 2. Cell-free haemolymph of larvae of Galleria mellonella previously injected with latex beads, stimulates in new larvae phagocytosis of Bacillus thuringiensis subtoxicus after transfusion. 3. The fractionation of homogenates of latex-treated larvae on Sephadex G 50 shows two fractions which stimulate phagocytosis. We suppose that the appearance of these phagocytosis-stimulating factors is the result of a successful recognition of foreign material.
Topics: Animals; Bacillus thuringiensis; Larva; Latex; Lepidoptera; Microspheres; Phagocytosis
PubMed: 543373
DOI: No ID Found -
Veterinary Research 2009Haemophilus parasuis is a colonizer of the upper respiratory tract of healthy pigs, but virulent strains can cause a systemic infection characterized by fibrinous...
Haemophilus parasuis is a colonizer of the upper respiratory tract of healthy pigs, but virulent strains can cause a systemic infection characterized by fibrinous polyserositis, commonly known as Glässer's disease. The variability in virulence that is observed among H. parasuis strains is not completely understood, since the virulence mechanisms of H. parasuis are largely unknown. In the course of infection, H. parasuis has to survive the host pulmonary defences, which include alveolar macrophages, to produce disease. Using strains from different clinical backgrounds, we were able to detect clear differences in susceptibility to phagocytosis. Strains isolated from the nose of healthy animals were efficiently phagocytosed by porcine alveolar macrophages (PAM), while strains isolated from systemic lesions were resistant to this interaction. Phagocytosis of susceptible strains proceeded through mechanisms independent of a specific receptor, which involved actin filaments and microtubules. In all the systemic strains tested in this study, we observed a distinct capsule after interaction with PAM, indicating a role of this surface structure in phagocytosis resistance. However, additional mechanisms of resistance to phagocytosis should be explored, since we detected different effects of microtubule inhibition among systemic strains.
Topics: Animals; Haemophilus parasuis; Macrophages, Alveolar; Phagocytosis; Pulmonary Alveoli; Swine; Time Factors; Virulence
PubMed: 19239855
DOI: 10.1051/vetres/2009007 -
European Journal of Immunology Jan 2008Phagocytosis and intracellular destruction of pathogens by phagocytes is a crucial defense mechanism of the innate immune response during infection. It has been reported...
Phagocytosis and intracellular destruction of pathogens by phagocytes is a crucial defense mechanism of the innate immune response during infection. It has been reported a number of times that the interaction with pyogenic, extracellular bacteria leads to the apoptotic death of phagocytes. The signaling events that cause this form of cell death are largely unknown. In this study, we demonstrate a link between uptake, killing and degradation of Escherichia coli bacteria and induction of apoptosis in macrophages. Treatment of murine RAW 264.7 macrophages with bafilomycin A(1), a phagosome acidification inhibitor, reduced killing and degradation of phagocytosed bacteria and significantly decreased macrophage apoptosis. The stable overexpression of constitutively active or dominant-negative mutants of the small GTPase Rab5a increased bacterial phagocytosis and consecutively apoptosis. In these cells, relative killing and degradation were not affected, linking the increased apoptosis to enhanced uptake and suggesting that the apoptosis-inducing signal derives from the higher incidence of degradation events or an accumulation of phagosomes of a late maturation stage. These results thus provide a link between bacterial phagocytosis and degradation and the induction of apoptosis in macrophages. We propose that this form of apoptosis is the physiological conclusion of an innate immune response against pyogenic bacteria.
Topics: Animals; Antifungal Agents; Apoptosis; Blotting, Western; Escherichia coli; Fluorescent Antibody Technique; Macrolides; Macrophages; Mice; Mutation; Phagocytosis; Transfection; rab5 GTP-Binding Proteins
PubMed: 18085665
DOI: 10.1002/eji.200737379 -
Investigative Ophthalmology & Visual... Dec 1989Confluent human trabecular meshwork (HTM) cells from three different donors and at various stages of serial passage were fed fluorescein-labeled polystyrene beads....
Confluent human trabecular meshwork (HTM) cells from three different donors and at various stages of serial passage were fed fluorescein-labeled polystyrene beads. Phagocytosis was monitored for up to 6 days using flow cytometry, fluorescence microscopy, and morphometric calculations from comprehensive electron microscopic observations at key time points. During the first 4 hr after initiation of phagocytosis, the confluent endothelial monolayer lost its cohesiveness and became segregated into separate cells. During the first 3 days the cells underwent marked and progressive changes in shape and size. After 4 days, some cells detached from the dish, as necrotic debris and degenerative changes appeared. The kinetics of phagocytosis in this stable, confluent monolayer showed that recruitment (the percentage of cells which had ingested at least one bead) proceeded semilogarithmically, with 50% of the cells recruited by 8 hr and 97% by 96 hr. The time course of phagocytosis (ie, the average number of beads phagocytosed per cell) is described by a sigmoidlike curve, reaching half-maximum at 40 hr and maximum (about 500 beads per cell) at 96 hr. The rate of uptake (ie, the first derivative of the average number of beads per cell) reached a peak (nine beads per cell per hr) at 24 hr and then decelerated slowly over the next 5 days. Cytochalasin B treatment, as a control, reduced phagocytosis by approximately 70%. Flow cytometry, when combined with electron microscopy, should provide a useful tool to examine phagocytosis in HTM cells exposed to steroids and other hormones and drugs.
Topics: Adult; Cells, Cultured; Cytochalasin B; Endothelium; Flow Cytometry; Humans; Kinetics; Microscopy, Fluorescence; Microspheres; Phagocytes; Phagocytosis; Regression Analysis; Trabecular Meshwork
PubMed: 2592162
DOI: No ID Found -
Dermatologic Surgery : Official... Jun 2002Foreign substances have been introduced into the human body with varying degrees of success. Polymethylmethacrylate (PMMA) microspheres of different sizes recently have...
BACKGROUND
Foreign substances have been introduced into the human body with varying degrees of success. Polymethylmethacrylate (PMMA) microspheres of different sizes recently have been manufactured for use as a filler substances in the skin and other organs.
OBJECTIVE
To establish whether the size of PMMA microspheres determines whether various cell types initiate phagocytosis.
METHODS
The capacity of three different cell lines-U-937 cells, XS 106 and XS 52 Langerhans cells, and HaCaT keratinocytes-to phagocytose microspheres of varying sizes was examined using light and confocal microscopy as well as fluorescence-activated cell sorter (FACS) analysis. Tumor necrosis factor (TNF)-alpha secretion was also determined.
RESULTS
The U-937 cells, keratinocytes, and Langerhans cells could phagocytose PMMA particles of 20 microm or smaller. Microspheres larger than 20 microm were not ingested by any of the cells.
CONCLUSION
Microspheres larger than 20 microm have a lower likelihood of being phagocytosed. Thus this study suggests that microspheres 40-50 microm in diameter are less likely to initiate an inflammatory reaction when injected into the dermis and subdermis as a filler substance. On the other hand, microparticles made of silicone and polymethacrylate were phagocytosed, possibly because of their different structure.
Topics: Biocompatible Materials; Cells, Cultured; Flow Cytometry; Humans; Keratinocytes; Macrophages; Microscopy, Confocal; Microspheres; Particle Size; Phagocytosis; Polymethyl Methacrylate; Prostheses and Implants; Skin; Tumor Necrosis Factor-alpha
PubMed: 12081676
DOI: 10.1046/j.1524-4725.2002.01273.x -
Journal of Medical Microbiology Feb 1985Phagocytosis by human leukocytes, phagosomal pH and degradation of seven species of bacteria were studied by a flow cytometric method. The percentage of phagocytosing...
Phagocytosis by human leukocytes, phagosomal pH and degradation of seven species of bacteria were studied by a flow cytometric method. The percentage of phagocytosing leukocytes was similar for all bacterial strains examined, but Salmonella typhi and Neisseria meningitidis were more slowly phagocytosed than other bacteria. The phagosomal pH surrounding the different bacterial species 15 min after the start of phagocytosis were: Streptococcus pneumoniae 4.4; N. meningitidis 4.9; Str. pyogenes 5.1; Staphylococcus aureus 5.2; Escherichia coli 5.3; S. typhi 5.4; and Klebsiella pneumoniae 5.7. For longer incubation periods, the phagosomal pH remained nearly constant. Staph. aureus, E. coli and S. typhi were the most readily degraded of the species tested. The proteins of all bacteria were degraded more rapidly than their DNA as determined by measurements of the loss of fluorescein-isothiocyanate-fluorescence and ethidium bromide-fluorescence, respectively. The rate of degradation varied from one bacterial species to another. The degradation of proteins and DNA was maximal for bacteria residing in a phagosomal environment estimated to be between pH 5.2 and 5.4.
Topics: Bacteria; Bacterial Proteins; DNA, Bacterial; Flow Cytometry; Humans; Hydrogen-Ion Concentration; Leukocytes; Phagocytes; Phagocytosis
PubMed: 3968704
DOI: 10.1099/00222615-19-1-115 -
Journal of Neuroendocrinology Dec 2003We observed in previous studies on avian heterophils that incubation with either physiological or pharmacological concentrations of the neurohormone melatonin increased...
We observed in previous studies on avian heterophils that incubation with either physiological or pharmacological concentrations of the neurohormone melatonin increased the phagocytosis of inert particles (latex beads), and also provoked a decline in superoxide anion levels of those phagocytes. In the present study, we wanted to corroborate whether melatonin acts on the oxidative metabolism that accompanies the respiratory burst during phagocytosis by inducing a more effective phagocytic activity at the same time as exerting an antioxidant effect to eliminate and/or scavenge the free radicals left over after the destruction of the foreign material. To this end, we evaluated the ingestion and destruction of Candida albicans (live particles) by ring dove (Streptopelia risoria) heterophils after different times of incubation (30 and 60 min) with physiological concentrations of melatonin (50 pg/ml diurnal and 300 pg/ml nocturnal), as well as with a pharmacological concentration 23 x 106 pg/ml (100 micro m) of the hormone. In parallel, using the same times of incubation, we evaluated the oxidative metabolism by determining the superoxide anion levels (O2-.). The results show that melatonin, at all the times and concentrations studied, increases both the phagocytosis index (number of C. albicans phagocytosed by 100 heterophils) and the candidicide power (percentage of C. albicans killed of those ingested by 100 heterophils). The effect was dose-dependent. With respect to the oxidative metabolism accompanying the digestion and destruction, there was a decline in superoxide anion levels after incubation with all of the concentrations of the hormone studied. The effect was dose-dependent and most pronounced at 60 min. These results thus corroborate the proposal that melatonin enhances the phagocytic function at the same time as neutralizing the oxidative stress derived from this immune function.
Topics: Animals; Antigens, Heterophile; Candida albicans; Candidiasis; Columbidae; Female; Free Radical Scavengers; Male; Melatonin; Oxidative Stress; Phagocytosis; Respiratory Burst; Superoxides
PubMed: 14636172
DOI: 10.1111/j.1365-2826.2003.01103.x -
Medecine Sciences : M/S Nov 2018
Topics: Animals; Cell Membrane Structures; Cell Polarity; Hyaluronan Receptors; Immunity, Innate; Membrane Fluidity; Membrane Proteins; Phagocytosis
PubMed: 30526842
DOI: 10.1051/medsci/2018244 -
Biosensors & Bioelectronics 2012The uptake of large particles by cells (phagocytosis) is an important factor in cell biology and also plays a major role in biomedical applications. So far, most methods...
The uptake of large particles by cells (phagocytosis) is an important factor in cell biology and also plays a major role in biomedical applications. So far, most methods for determining the phagocytic properties rely on cell-culture incubation and end-point detection schemes. Here, we present a lab-on-a-chip system for real-time monitoring of magnetic particle uptake by human fibroblast (NHDF) cells. It is based on recording the time evolution of the average position and distribution of magnetic particles during phagocytosis by giant-magnetoresistive (GMR) type sensors. We employ particles with a mean diameter of 1.2 μm and characterize their phagocytosis-relevant properties. Our experiments at physiological conditions reveal a cellular uptake rate of 45 particles per hour and show that phagocytosis reaches saturation after an average uptake time of 27.7h. Moreover, reference phagocytosis experiments at 4°C are carried out to mimic environmental or disease related inhibition of the phagocytic behavior, and our measurements clearly show that we are able to distinguish between cell-membrane adherent and phagocytosed magnetic particles. Besides the demonstrated real-time monitoring of phagocytosis mechanisms, additional nano-biointerface studies can be realized, including on-chip cell adhesion/spreading as well as cell migration, attachment and detachment dynamics. This versatility shows the potential of our approach for providing a multifunctional platform for on-chip cell analysis.
Topics: Biosensing Techniques; Cell Line; Fibroblasts; Humans; Magnetite Nanoparticles; Microfluidic Analytical Techniques; Phagocytosis
PubMed: 22560105
DOI: 10.1016/j.bios.2012.04.002 -
Acta Histochemica 2003Experiments were carried out to investigate whether different lymphatic tumour cell lines have similar kinetic characteristics of phagocytosis of microorganisms. Six... (Comparative Study)
Comparative Study
Experiments were carried out to investigate whether different lymphatic tumour cell lines have similar kinetic characteristics of phagocytosis of microorganisms. Six tumour cell lines were used. These were a human T-cell line (CEM), a mouse T-cell line (YAC-1), a human B-cell line (LAZ), and a human erythroleukemic tumour cells (K562), whereas 2 cell lines of professional phagocytosis were used as controls, a human macrophage cell line (THP1) and a mouse macrophage cell line (P388D1). Tumour cells were mixed with candida albicans at a ratio of 10:1 of candida to tumour cells and the percentage of tumour cells that had attached/phagocytosed candida was determined. After 4 h coculture with candida, tumour cells not of T-cell origin (LAZ and K562) showed moderate level of phagocytosis (28%), whereas tumour cells of T-cell origin (CEM and YAC-1) demonstrated low levels of phagocytosis (15%) as compared to macrophage cell lines (THP1 and P388D1) that showed maximum phagocytosis (64-78%). Acid phosphatase (AcPase) activity was increased by 33% during coculture of YAC-1 cells and yeast cells. In conclusion, the results suggest that lymphatic tumour cells of nonphagocytic origin acquire phagocytic properties during the course of malignancy, and digestion of phagocytosed yeast cells maybe related with AcPase activity, as well as that of other lysosomal enzymes. This phenomenon may represent one mechanism by which tumour cells downregulate immune surveillance.
Topics: Acid Phosphatase; Animals; Candida albicans; Cell Line; Cell Line, Tumor; Coculture Techniques; Humans; K562 Cells; Mice; Phagocytosis; Time Factors
PubMed: 12831164
DOI: 10.1078/0065-1281-00704