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1.
During phagocytosis, macrophages rapidly internalize a substantial fraction of plasma membrane without a net loss of surface area, suggesting that membranes are targeted to the cell surface from intracellular sites. Nevertheless, a requirement for mobilization of specific membrane compartments has not been demonstrated. We used bone marrow-derived macrophages (BMM) from wild type and vamp3 null mice to evaluate directly the requirement for this v-SNARE in phagocytosis of zymosan, IgG-beads, complement-opsonized particles, or latex microspheres. Regardless of the phagocytic receptor engaged or particle load, BMM lacking vamp3 exhibited no phagocytic defects when assayed after 1 h at 37 degrees C, and phagosome maturation was unimpaired as judged by acquisition of lamp-1. In contrast, at early time points (5-15 min), internalization of zymosan (but not other particles tested) was significantly slower in vamp3 null BMM. These data indicate that vamp3 modulates efficient uptake of zymosan, but is not absolutely required for phagocytosis in primary macrophages.  相似文献   

2.
The phagocytosis of uniform fluorescent latex particles by resident and thioglycollate-elicited macrophages was analysed by flow cytometry. The percentage of phagocytosing macrophages and the number of internalized microspheres per cell was determined from cell size and fluorescence histograms. Results were corrected for the adherence of microbeads to the cells in the presence of sodium azide in the medium. Human C3b- or murine monoclonal IgG-coated microspheres were applied to assess receptor-mediated phagocytosis in different inbred strains of mice. Phagocytic activity of thioglycollate-elicited macrophages was consequently higher than that of resident macrophages. A decreasing gradient of C3b and Fc receptor-mediated phagocytosis was established in the following order: B10.BR, B10, C3H/Di and C3H.SW strains. Our results indicate that the phagocytic function of murine macrophages is under control of both the somatic (non-H-2) and H-2 genes.  相似文献   

3.
The phagocytosis of uniform fluorescent latex particles by resident and thiogiycollate-elicited macrophages was analysed by flow cytometry. The percentage of phagocytos-ing macrophages and the number of internalized microspheres per cell was determined from cell size and fluorescence histograms. Results were corrected for the adherence of microbeads to the cells in the presence of sodium azide in the medium. Human C3b-or murine monoclonal IgG-coated microspheres were applied to assess receptor-mediated phagocytosis in different inbred strains of mice. Phagocytic activity of thioglycollate-elicited macrophages was consequently higher than that of resident macrophages. A decreasing gradient of C3b and Fc receptor-mediated phagocytosis was established in the following order: B10.BR, BIO, C3H/Di and C3H.SW strains. Our results indicate that the phagocytic function of murine macrophages is under control of both the somatic (non-H-2) and H-2 genes.  相似文献   

4.
One of the major host-defense functions of alveolar macrophages is the phagocytosis and clearance of inhaled particles deposited in the lower airways and alveolar spaces. Recent studies have indicated that the condensed tannins present in cotton mill dust stimulate the secretion of neutrophil chemotactic factor and arachidonic acid from resident rabbit alveolar macrophages and that these responses may contribute to the acute pulmonary inflammatory reaction associated with byssinosis. To characterize further the effect of tannin on macrophage function, the ability of tannin to modulate alveolar macrophage spreading and phagocytosis in vitro was examined. Tannin caused a dose-dependent inhibition of alveolar macrophage spreading with nearly complete inhibition occurring at concentrations of 12.5 micrograms/ml. This inhibitory effect of tannin was not reversed with removal of tannin. Furthermore addition of tannin to previously spread macrophages actively caused the macrophages to round up. Examination of the structure of alveolar macrophages exposed to tannin by scanning and transmission electron microscopy revealed blebs on the surface of the cells and the loss of most of the cellular organelle structure, as compared to control macrophages. Tannin also modulated the ability of the alveolar macrophages to phagocytize unopsonized latex microspheres. The effect of tannin was biphasic. At the lowest concentration examined (3 micrograms/ml), tannin significantly enhanced phagocytosis of the latex microspheres. However, as the concentration was increased, phagocytosis decreased almost exponentially until at 50 micrograms/ml phagocytosis was significantly inhibited compared to control macrophages. These data indicate that tannin present in inhaled cotton mill dust could significantly decrease the ability of resident alveolar macrophages to phagocytize and thereby clear inhaled dust particles. This inhibitory effect would increase the time that particles remain exposed in the lower airway and alveolar spaces and thereby increase the time that potentially toxic compounds in the dust have to exert their biologic effect. This inhibition of macrophage function may therefore contribute to the pathogenesis of byssinosis.  相似文献   

5.
A variety of biodegradable microspheres were prepared from L-lactic acid, DL-lactic acid, or glycolic acid homopolymers and copolymers of different molecular weights and monomer compositions. Phagocytosis of the microspheres by mouse peritoneal macrophages was studied in cell culture system using scanning electron microscopy as well as light microscopy. The diameter of microspheres prepared was less than 2 microns, regardless of the starting polymers. No dependence of the chemical nature of starting polymers was observed on the extent of phagocytosis of the microspheres by macrophages. Precoating the microspheres with water-soluble macromolecules such as proteins had great influence on phagocytosis by macrophages. It was demonstrated that precoating with bovine serum albumin and non-proteinaceous macromolecules reduced the phagocytosis of microspheres, while bovine gamma-globulin, human fibronectin, bovine tuftsin, and gelatin precoating enhanced the phagocytosis. This trend was not influenced by the presence of serum. Only in the case of gelatin precoating, the phagocytosis was greatly enhanced by the presence of serum as compared to precoating with other proteins. Microscopic observation clearly indicated that the phagocytosed microspheres were gradually degraded in the macrophage interior with the incubation time, leading to release of a fluorescent dye encapsulated in the microspheres. The rate of microsphere degradation in cells could be controlled by changing the molecular weight and the monomer composition of the copolymers comprising the microspheres.  相似文献   

6.
Experiments were conducted to test the hypothesis that opsonic and non-opsonic phagocytic capacities are differentially regulated by resting and wound-derived macrophages. Furthermore, the phagocytosis of non-opsonized zymosan and beta-glucan particles was quantified to determine whether cells differentially regulate non-opsonic lectinophagocytosis in accordance with the carbohydrate composition of the ligand. In that regard, wound macrophages exhibited profound differential regulation in lectinophagocytosis with a seven-fold increase in phagocytosis of beta-glucan particles following overnight culture but with a relatively modest increase in internalization of mannan-containing zymosan. Cultured peritoneal macrophages increased uptake of both particles similarly. Upon activation with interferon-gamma/lipopolysaccharide (IFN-gamma/LPS), wound macrophages selectively suppressed beta-glucan ingestion, while phagocytosis of zymosan particles was unaffected. Lectinophagocytosis was decreased in activated peritoneal macrophages regardless of particle composition and was due in part to a nitric oxide-dependent mechanism which was without a role in regulation of wound macrophage lectinophagocytosis. Overnight culture of wound macrophages suppressed their capacity for opsonic-dependent phagocytosis independently of activation, whereas suppression of phagocytosis by peritoneal macrophages was activation-dependent. Regulation of all three phagocytic pathways was achieved distinctly by peritoneal and wound-derived macrophages, with changes found in the percentage of resident peritoneal macrophages capable of phagocytosis, whereas the phagocytic capacity of wound macrophages was primarily affected by the number of particles ingested by individual cells. Taken together, these findings demonstrate that the differential regulation of phagocytic pathways encompasses the nature of the phagocytic particle, the site from which macrophages are obtained, their response to activating agents and the mechanism through which the cell population alters its phagocytic potential.  相似文献   

7.
Glucocorticoid steroids inhibit phagocytosis and cell spreading in cultures of murine resident peritoneal macrophages. It is postulated that these suppressive responses are mediated by a steroid-induced substance elaborated from dexamethasone-treated macrophages. Accordingly, dialyzed medium from dexamethasone-treated cultures was analyzed for the presence of a factor that inhibits phagocytosis and cell spreading in macrophage cultures not exposed to the steroid. When previously untreated macrophages were supplied dialysates from steroid-treated cultures, cell spreading and the phagocytic capacity (i.e. percentages of phagocytes in macrophage populations and the ability of phagocytes to ingest heat-killed Saccharomyces cerevisiae particles) decreased dramatically between 2 and 24 h after exposure. A lesser transient inhibitory response was observed when dialysates from untreated cultures were used. Relative to these controls after 48 h, phagocytic capacity and cell spreading remained suppressed in cultures treated with dialysates from dexamethasone-treated cultures. The addition of arachidonate, in the absence and presence of cyclooxygenase and lipoxygenase inhibitors, did not affect the phagocytic capacity of control macrophages. Furthermore, the addition of these compounds, either alone or in combination, to dexamethasone-treated cultures did not modulate the steroid-induced suppression of phagocytosis. These results support the hypothesis that the inhibition of phagocytosis and cell spreading may be mediated by a dexamethasone-induced non-dialyzable factor. In addition, the inability of arachidonic acid and inhibitors of prostaglandin and leukotriene biosynthesis to reverse the steroid-induced suppression of phagocytosis implies that the inhibition of this important macrophage function is not associated with the failure of dexamethasone-treated macrophages to release these mediators.  相似文献   

8.
Morphology and phagocytosis of macrophages were studied after cultured under cyclic strain. Peritoneal macrophages obtained from 6-week old female C57BL/6J mice were attached to silicone rubber sheets, preincubated for 2 hours, and then cultured for 24 and 48 hours under cyclic strain of 5% amplitude and 1 Hz frequency (strained group) or no strain (non-strained group). Control data were obtained from 0-hour cultured cells (control group). Cell morphology was observed with optical and scanning electron microscopes, and shape index (SI) of each cell was determined from the perimeter and adhesion area. Phagocytotic activity was evaluated from the uptake of latex particles 1.5 microm in diameter. The morphology and phagocytosis of macrophages were affected by cyclic strain, although the percentage of differentiated cells was not the case. SI in the strained group was smaller than that in the non-strained group, and had a tendency of decreasing with time. Cyclic strain suppressed the phagocytosis of macrophages for latex particles, and there was a significant difference in the phagocytosis between the strained and the non-strained groups after 24-hour culture.  相似文献   

9.
Y Tabata  Y Ikada 《Biomaterials》1988,9(4):356-362
Polystyrene and phenylated polyacrolein microspheres of different diameters, as well as modified cellulose microspheres with different surface charges, were prepared in order to study the size and surface charge effect on their phagocytosis by mouse peritoneal macrophages. It was found that the maximal phagocytosis of polystyrene and phenylated polyacrolein microspheres took place when their size was in the range 1.0-2.0 microns. Microspheres with hydrophobic surfaces were more readily phagocytosed than those with hydrophilic surfaces. There was no significant difference in phagocytosis between cationic and the anionic surfaces when compared at a zeta potential of the same absolute value. The least phagocytosis was observed for cellulose microspheres with non-ionic hydrophilic surfaces. Addition of fetal calf serum to the culture medium resulted in decrease in phagocytosis for all microspheres.  相似文献   

10.
Wear particles from prosthetic implants have been shown to cause inflammatory synovitis and periprosthetic osteolysis. These particle-induced pathologies are manifestations of adverse cellular responses to phagocytosed particles. In this study, phagocytosis of polyethylene particles was analyzed using flow cytometry (FCM), and the clinical utility of FCM in diagnosing particle-induced synovitis was examined.Ultra high molecular weight polyethylene particles exhibited natural autofluorescence at fluorescein isothiocyanate wavelengths when determined by FCM. Using this autofluorescent property of the particles, peripheral blood monocytes (PBMs) phagocytosing the particles could be detected by autofluorescence emission from intracellular particles. This autofluorescence from PBMs increased with particles/cell ratio in a dose-dependent manner. Particle phagocytosis was also detectable in joint fluid cells obtained from the patients with particle-induced synovitis following total joint arthroplasty (TJA). Phenotypic analysis indicated that phagocytes were typically CD14(+)CD16(-) macrophages, with occasional CD14(+)CD16(+) macrophages. Interestingly, decreased autofluorescence intensity of CD14(+) cells was observed after arthroscopic drainage, suggesting that FCM was useful in examining whether the treatment was successful. In summary, these results indicate that FCM analysis offers a simple and useful method of detecting phagocytosis of polyethylene particles and estimating the severity of particle-induced synovitis in post-TJA patients.  相似文献   

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