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Journal of Immunology (Baltimore, Md. :... Dec 2006Immunization with particulate Ag effectively induces antitumor and antiviral T cell-mediated immunity. Immature dendritic cells (DCs) efficiently internalize, process,...
Immunization with particulate Ag effectively induces antitumor and antiviral T cell-mediated immunity. Immature dendritic cells (DCs) efficiently internalize, process, and present a variety of particulate Ags; however, previously published data suggest that both the uptake of soluble Ag through micropinocytosis, and phagocytosis of particulates are significantly curtailed in activated DC populations. In this study, we demonstrate that although macropinocytosis of soluble Ag is diminished following DC activation, subsets of DCs in activated DC populations retain the ability to actively phagocytose particulate Ags. Live cell imaging of activated DCs reveals that phagocytosis of particulates can result in cytoskeletal remodeling and perinuclear lysosome cluster disruption in a time-dependent manner. Interestingly, our results suggest that in activated DC populations, presentation of phagocytosed particulate Ags is dependent on the nature of the activation signal. These results provide direct evidence of functional heterogeneity in DC populations and contribute to the development of particle-based immunization strategies.
Topics: Animals; Antigen Presentation; Antigens; Bone Marrow Cells; Cells, Cultured; Cytoskeleton; Dendritic Cells; Female; Lysosomes; Mice; Mice, Inbred C57BL; Phagocytosis; Pinocytosis; Solubility
PubMed: 17142747
DOI: 10.4049/jimmunol.177.12.8493 -
Acta Paediatrica (Oslo, Norway : 1992) Apr 2006To determine the phagocytic activity of the polymorphonuclear and mononuclear cells present in human colostrum, and to verify the influence of opsonins in the adherence,...
AIM
To determine the phagocytic activity of the polymorphonuclear and mononuclear cells present in human colostrum, and to verify the influence of opsonins in the adherence, ingestion and killing of Giardia lamblia trophozoites.
METHODS
Polymorphonuclear and mononuclear phagocytes were incubated with G. lamblia trophozoites, in the presence as well as the absence of supernatant of human colostrum (the source of opsonins) for 30, 60 and 120 min. The trophozoites/phagocytes ratio was 1:1, and the percentage of phagocytosed trophozoites was determined by microscopic examination of acridine orange-stained cells.
RESULTS
The mononuclear phagocytes presented more functional activity than the polymorphonuclear. The highest indexes of adherence (77.6 +/- 5.1), ingestion (68.9 +/- 5.5) and killing (48.5 +/- 4.9) were obtained through the incubation of mononuclear cells in the presence of colostrum supernatant for 120 min.
CONCLUSION
The phagocytes of human colostrum were able to ingest G.lamblia trophozoites and presented microbicidal activity in vitro, suggesting that these phagocytes may act as an additional mechanism of protection against infant giardiasis through breastfeeding.
Topics: Adolescent; Adult; Animals; Cell Culture Techniques; Colostrum; Female; Giardia lamblia; Humans; Leukocytes, Mononuclear; Microbial Viability; Opsonin Proteins; Phagocytes; Phagocytosis; Pregnancy
PubMed: 16720491
DOI: 10.1080/08035250500421592 -
Journal of Biomolecular Screening Sep 2010Phagocytosis is a critical host defense mechanism that clears invading pathogens, apoptotic cells, and cell debris; it is an essential process for normal development,...
Phagocytosis is a critical host defense mechanism that clears invading pathogens, apoptotic cells, and cell debris; it is an essential process for normal development, tissue remodeling, immune response, and inflammation. Here, a functional selection strategy was used to isolate novel phagocytosis-promoting genes. After the retroviral transfer of mouse brain cDNA library into NIH3T3 mouse fibroblast cells, cell sorting was used to select the cells that phagocytosed fluorescent zymosan particles. The cDNAs were retrieved from the selected cells and identified by DNA sequencing as eIF5A, Meg3, Tubb5, Sparcl-1, Uchl-1, Bsg (CD147), Ube2v1, and Pamr1. The phagocytosis-promoting activity for some of these cDNAs was confirmed by transient transfection in the independent phagocytosis assays. Thus, the unbiased selection procedure successfully identified multiple phagocytosis-promoting genes. The selection method can be applied to other cell-based assays where cells with a desired phenotype can be physically separated. Moreover, the new gene targets uncovered in this study could be relevant to biomolecule screening in search of phagocytosis-regulating agents. In a small-scale screen, a series of imidazopyridine compounds was tested to identify the small molecules that modulate eIF5A-mediated phagocytic activity. Several compounds that influenced the phagocytic activity can be further used as chemical-genetic tools to delineate the mechanisms of eIF5A action and be potential drug candidates that are capable of therapeutically modulating phagocytic activity.
Topics: Animals; Cell Proliferation; Cell Separation; Cells, Cultured; Cloning, Molecular; Flow Cytometry; Gene Library; Genes; High-Throughput Screening Assays; Mice; Models, Biological; NIH 3T3 Cells; Nucleic Acid Synthesis Inhibitors; Phagocytosis; Phenotype; Transfection
PubMed: 20660795
DOI: 10.1177/1087057110376090 -
Acta Pathologica, Microbiologica, Et... Feb 1984Phagocytosis of killed, fluorochrome stained or live Staphylococcus aureus by human leukocytes was measured by flow cytometry (FCM) or a microbiological method,... (Comparative Study)
Comparative Study
Phagocytosis of killed, fluorochrome stained or live Staphylococcus aureus by human leukocytes was measured by flow cytometry (FCM) or a microbiological method, respectively. The results were compared to those obtained by simulation using a prey-predator model. In the presence of an initial bacteria-to-phagocyte ratio of 4:1 to 160:1, the percentage of phagocytosing leukocytes was independent of the bacteria and phagocyte concentration. The number of phagocytosed or killed bacteria per phagocyte increased with increasing bacteria and decreasing phagocyte concentration. One per cent pooled human serum was sufficient for maximum phagocytosis to occur, but killing slightly increased in the presence of 10% pooled human serum. With medium or low initial bacteria-to-phagocyte ratios phagocytosis and killing closely corresponded to the results obtained by the prey-predator model. Maximally each phagocyte was associated with 80 bacteria (measured by FCM), about 45 being phagocytosed (internalized) and 40 killed. The model seems suitable for the simulation of phagocytosis and killing of S. aureus by human leukocytes.
Topics: Adhesiveness; Bacteriological Techniques; Blood Bactericidal Activity; Flow Cytometry; Humans; Models, Biological; Neutrophils; Phagocytosis; Staphylococcus aureus
PubMed: 6369877
DOI: 10.1111/j.1699-0463.1984.tb00050.x -
The Journal of Antimicrobial... Oct 1983We studied the effect of clindamycin on phagocytosis of Bacteroides fragilis (MIC = 0.05 mg/l). In the in-vitro test system phagocytosis of Bact. fragilis was less than...
We studied the effect of clindamycin on phagocytosis of Bacteroides fragilis (MIC = 0.05 mg/l). In the in-vitro test system phagocytosis of Bact. fragilis was less than 11% for the first 30 min of incubation. At 60 min, 25-50% of Bact. fragilis were phagocytosed. At 90 min, phagocytosis increased to 60% of the bacterial inoculum and did not increase thereafter. When clindamycin (0.02 mg/l) was incubated with neutrophils for 2 h prior to exposure to bacteria, there was no increase in phagocytosis. When clindamycin (0.02 mg/l) was incubated with bacteria for 2 h before exposure to neutrophils, phagocytosis increased to 23.1 +/- 5.9 (S.D.) per cent at 30 min compared to 1.1 +/- 15.1% (P less than 0.05) for bacteria not exposed to clindamycin. There was no difference in phagocytosis between the two groups at 60 and 90 min. One-fifth the MIC (0.01 mg/l) but not 0.004 mg/l also led to increased phagocytosis at 30 min but not at 60 min if previously incubated with clindamycin. Thus, clindamycin potentiates phagocytosis of Bact. fragilis. It can act directly on bacteria and promote phagocytosis, although the clinical importance of this last mode of action is not currently known.
Topics: Bacteroides fragilis; Clindamycin; Humans; In Vitro Techniques; Phagocytosis; Stimulation, Chemical
PubMed: 6643342
DOI: 10.1093/jac/12.suppl_c.63 -
Journal of Biomechanics Sep 2014To better understand if a complex process such as phagocytosis is influenced by substrate stiffness, we investigated the influence of substrate elastic modulus on...
To better understand if a complex process such as phagocytosis is influenced by substrate stiffness, we investigated the influence of substrate elastic modulus on phagocytosis in the retinal pigment epithelial (RPE) cell line ARPE-19. RPE cells lie on Bruch's membrane, directly under the retina, and phagocytose the shed photoreceptor outer segments. Bruch's membrane is known to increase in stiffness by an order of magnitude with age and thus, this study has potential relevance in explaining retinal changes in age-related macular degeneration. ARPE-19 cells were plated on laminin-coated polyacrylamide substrates of varying elastic modulus. After 14 days in culture, a solution of latex fluorescent beads suspended in PBS was placed in each well. After an incubation time of 4h, flow cytometry was performed to determine the number of cells that phagocytosed a bead. The number of ARPE-19 cells that phagocytosed a bead decreased continuously as a function of increasing substrate elastic modulus (p=0.0135), and this was found to be a linear relationship (slope=-0.03305 ± 0.01104, R2=0.4726 per 10,000 cells). Our results suggest that RPE cells display decreased phagocytosis when grown on firmer substrates, and thus, RPE cells in older eyes, in which Bruch's membrane is stiffer, may demonstrate decreased phagocytosis. Impaired phagocytosis by RPE cells may contribute to impaired metabolism of photoreceptor outer segments and to development of macular degeneration. Material stiffness may be a critical parameter in the development of neural therapies, including retinal prosthetics and stem cell therapies.
Topics: Acrylic Resins; Cell Culture Techniques; Cell Line; Elastic Modulus; Humans; Laminin; Microspheres; Phagocytosis; Pigment Epithelium of Eye
PubMed: 25016484
DOI: 10.1016/j.jbiomech.2014.06.021 -
Journal of Leukocyte Biology Nov 1985Human monocyte-derived macrophages phagocytosed zymosan in the absence of serum opsonins. The capacity to ingest zymosan developed after the cells were cultured in vitro...
Human monocyte-derived macrophages phagocytosed zymosan in the absence of serum opsonins. The capacity to ingest zymosan developed after the cells were cultured in vitro for 3 days and was inhibited completely by mannan. We conclude that human monocyte-derived macrophages phagocytose unopsonized zymosan predominantly via mannose receptors.
Topics: Humans; Lectins, C-Type; Macrophages; Mannans; Mannose Receptor; Mannose-Binding Lectins; Opsonin Proteins; Phagocytosis; Receptors, Cell Surface; Receptors, Immunologic; Zymosan
PubMed: 3862731
DOI: 10.1002/jlb.38.5.655 -
Journal of Chemotherapy (Florence,... Oct 1993Activation of non-specific host defenses can increase resistance to infection in patients and especially those with reduced immune response. Thymomodulin is a calf...
Activation of non-specific host defenses can increase resistance to infection in patients and especially those with reduced immune response. Thymomodulin is a calf thymic derivative containing low molecular weight peptides, which exerts immunomodulating activity probably through an enhancement of lymphocyte functions. To explore this possibility, rat macrophages (MP) and human polymorphonuclear (HPMN) cells were incubated in vitro with 100, 200, 400 micrograms/ml of thymomodulin at 37 degrees C for 60 min and their phagocytic activity was investigated. The number of phagocytosing cells was significantly increased following increasing concentrations of thymomodulin and the percentage of phagocytosis was increased more for human PMNs in comparison with rat MP, while the values of the phagocytic index were not modified after challenge with thymomodulin both for MPs and HPMNs.
Topics: Animals; Humans; In Vitro Techniques; Macrophages; Neutrophils; Phagocytosis; Rats; Thymus Extracts
PubMed: 8106905
DOI: 10.1080/1120009x.1993.11739251 -
Proceedings of the Society For... Nov 1983A new method has been developed for the evaluation of the phagocytic activity of human leukocytes using fluorescently labeled bacteria and flow cytometry. By...
A new method has been developed for the evaluation of the phagocytic activity of human leukocytes using fluorescently labeled bacteria and flow cytometry. By simultaneous measurement of cellular light scatter and fluorescence, extracellular bacteria, phagocytes, and nonphagocytes could be discriminated and quantified. All leukocytes assumed to be capable of phagocytosis were phagocytosing, and about 90% of these cells were polymorphonuclear neutrophilic granulocytes. Within 15 min 85% of the bacteria were phagocytosed and each phagocyte contained an average of 15-20 bacteria. The phagocytic capacity of the leukocytes from healthy individuals showed minor interindividual and day-to-day variations. This method facilitates a rapid and accurate in vitro evaluation of the phagocytic activity of human leukocytes.
Topics: Bacteria; Cell Separation; Flow Cytometry; Fluorescein-5-isothiocyanate; Fluoresceins; Granulocytes; Humans; In Vitro Techniques; Leukocytes; Neutrophils; Phagocytosis; Thiocyanates
PubMed: 6415659
DOI: 10.3181/00379727-174-41722 -
Neuro-oncology Jul 2000Apoptotic cells display signals that trigger phagocytic removal by macrophages or neighboring cells. To better understand the signals triggering phagocytosis of...
Apoptotic cells display signals that trigger phagocytic removal by macrophages or neighboring cells. To better understand the signals triggering phagocytosis of apoptotic glioma cells, and to identify the cells that might be involved in the phagocytic process, U-251 MG glioma cells were made apoptotic by etoposide (25 microg/ml) treatment and were incubated with normal human astrocytes (NHA), glioma cells, or microglia. Extent of phagocytosis was assessed by an in vitro phagocytosis assay. After 3 h of incubation with apoptotic cells, phagocytes tested were washed to remove nonengulfed cells, then fixed, stained, and counted to determine phagocytosis index (PI). NHA, glioma cells, and microglia all phagocytosed apoptotic, but not nonapoptotic, glioma cells. Microglia, however, had a PI approximately 4-fold higher than did either NHA or glioma cells. Binding of phosphatidylserine (PS) on apoptotic glioma cell membranes by annexin-V inhibited phagocytosis by 90% in both microglia and NHA. The activity of an enzyme (scramblase) that moves PS from the inner cell membrane to the outer cell membrane was also increased in apoptotic glioma cells. These results suggest that a variety of cells present in and near gliomas in vivo can remove glioma cells in a PS-dependent scramblase-mediated fashion. Manipulation of scramblase and/or PS exposure in glioma cells may therefore be a means of triggering phagocytic removal of glioma cells.
Topics: Apoptosis; Astrocytes; Brain; Carrier Proteins; Cell Line; Glioma; Humans; Membrane Proteins; Microglia; Phagocytosis; Phosphatidylserines; Phospholipid Transfer Proteins; Reference Values
PubMed: 11302338
DOI: 10.1093/neuonc/2.3.174