Showing papers on "Phagosome published in 1978"

Growth of Chlamydia psittaci in macrophages.

Abstract: Survival and growth of L-cell-cultivated Chlamydia psittaci occurred in mouse macrophages in vitro. Two major factors governing the intracellular fate of chlamydiae in macrophages are: (i) the multiplicity of infection (MOI), i.e., the elementary body (EB)-to-macrophage ratio, and (ii) the state of the EB. At a low MOI (1:1) survival and growth of live, untreated chlamydiae were optimal. The chlamydiae were internalized in macrophages within 30 to 40 min. EB proceeded to differentiate into reticulate bodies, which underwent multiplication and further matured into infectious EB in the professional phagocytic cells. In contrast, at a high MOI (100:1), survival of untreated chlamydiae was greatly reduced as a result of immediate damage to the macrophages. eb that were pretreated with heat (56 degrees C for 10 to 30 min) or coated with homologous antibody were rapidly destroyed in macrophage phagolysosomes. Fusion of ferritin-labeled lysosomes with heat-treated or opsonized EB-laden phagosomes occurred in 2 to 4 h, resulting in transfer of the ferritin marker into phagolysosomes.

Localization of D-amino acid oxidase on the cell surface of human polymorphonuclear leukocytes.

Abstract: The ultrastructural localization of D-amino acid oxidase (DAO) was studied cytochemically by detecting sites of hydrogen peroxide production in human polymorphonuclear leukocytes (PMNs). Reaction product, which forms when cerous ions react with H2O2 to form an electron-dense precipitate, was demonstrated on the cell surface and within the phagosomes of phagocytically stimulated cells when D-amino acids were provided as substrate. Resting cells showed only slight activity. The competitive inhibitor D,L-2-hydroxybutyrate greatly reduced the D-amino acid-stimulated reaction while KCN did not. The cell surface reaction was abolished by nonpenetrating inhibitors of enzyme activity while that within the phagosome was not eliminated. Dense accumulations of reaction product were formed in cells which phagocytosed Staphylococcus aureus in the absence of exogenous substrate. No reaction product formed with Proteus vulgaris while an intermediate amount formed when Escherichia coli were phagocytosed. Variation in the amount of reaction product with the different bacteria correlated with the levels of D-amino acids in the bacterial cell walls which are available for the DAO of PMNs. An alternative approach utilizing ferricyanide as an electron acceptor was also used. This technique verified the results obtained with the cerium reaction, i.e., the DAO is located in the cell surface and is internalized during phagocytosis and is capable of H2O2 production within the phagosome. The present finding that DAO is localized on the cell surface further supports the concept that the plasma membrane is involved in peroxide formation in PMNs.

Ultrastructural and immunological aspects of the phagocytosis of Trypanosoma brucei by mouse peritoneal macrophages.

Abstract: Trypanosome-activated mouse peritoneal macrophages phagocytized and digested Trypanosoma brucei in vitro and in vivo, but in the absence of specific antiserum and complement the degree of phagocytosis was minimal. Ultrastructurally, the parasites attached to the macrophage by their flagella, and ingestion proceeded flagellum first. Once ingested, T. brucei was degraded, presumably due to fusion of the parasite-containing phagosome with lysosomes. Contrariwise, normal mouse peritoneal macrophages displayed negligible ability to ingest T. brucei, even in the presence of specific antiserum and complement. During trypanosomiasis in deer mice (Peromyscus maniculatus), the development of hypergammaglobulinemia correlated with enhanced phagocytosis of T. brucei by macrophages, but only at early post-inoculation days (PID 5 to 15). Complement lysis of trypanosomes was not identified in these experiments. Between PID 20 to 30, antiserum and complement either had no phagocytosis-promoting ability or depressed the phagocytosis of T. brucei by macrophages. These results indicate that both specific antibody and complement contribute to the ingestion of T. brucei by activated macrophages, but that parasite antigenic variation effectively abrogates the phagocytic defense mechanism.

In vivo phagocytosis by developing myocardial cells: an ultrastructural study.

Abstract: Phagocytosis of naturally degenerating cells, by healthy myocardial cells of the bulbus cordis of 5--7-day chick embryos, was studied by electron microscopy. Myocardial cells showed cell processes surrounding dead cell fragments. The cell fragments appeared to be internalized later and digested within phagosomes. Ruthenium red was employed to ascertain whether the cell fragments were in fact internalized or located in pockets of the cell membrane. The results are discussed in the light of present knowledge of phagocytosis.

Role of the surface coat in in vitro attachment and phagocytosis of Plasmodium berghei by peritoneal macrophages.

Abstract: Evidence is presented to indicate that Plasmodium berghei merozoites, but not trophozotites, have an antiphagocytic capsule. The capsule appears to form around the developing merozoties of the schizont in the parasitophorous vacuole. Serum from animals immune to P. berghei reacts with this capsule. After reaction with immune serum, the antiphagocytic action of the capsule is lost. By the process of binding serum protein, the capsule becomes electron dense and can be readily visuallzed as the surface coat by electron microscopy. At physiological temperatures, phagocytosis by macrophages rapidly follows adhesion of antibody-coated parasites. Both tight and loose phagosomes are formed.

Entry of Trypanosoma (Schizotrypanum) dionisii to macrophages in vitro and its subsequent fate therein.

Abstract: Observations by phase contrast, fluorescence and electron microscopy showed that epimastigotes of Trypanosoma (Schizotrypanum) dionisii (grown in vitro) were phagocytosed posterior end first by mouse peritoneal macrophages in vitro. Many were subsequently digested as a result of phagosome-lysosome fusion but others survived by apparently inhibiting this fusion and/or escaping from the phagosome into the host cell's cytoplasm. These survivors replicated as amastigotes. Long trypomastigotes, separated from populations grown in vitro by passage down a column of glass beads (with or without prior exposure to guinea-pig serum), were phagocytosed by either pole and all were subsequently digested.

The early cellular response to M. leprae. An ultrastructural study.

Abstract: The ultrastructural changes that develop in mouse peritoneal macrophages from 10 minutes up to 14 weeks after exposure to Mycobacterium leprae are presented. Phagocytosis occurred by a process of engulfment by cytoplasmic processes and incorporation into a phagosome, into which lysosomal enzymes were subsequently introduced. Electron transparent zones (E.T.Z.) were not observed around phagocytosed bacilli in this study, however discrete droplets of lipid-like material appeared in the cytoplasm of macrophages, between 2 and 4 weeks after ingestion of the micro-organisms. Phagosomes with double limiting membranes were observed in macrophages harvested as early as 40 minutes after exposure to M. leprae, contrary to the observations of Evans and Levy (1972).

Cooperation of Complement (C) and Polymorphonuclear Leucocytes (PMN) in the ingestion, killing and destruction of C-resistant E. coli

Abstract: Attachment of bacteria to phagocytic cells is augmented by opsonins due to Fc and C3 receptors. It has also been shown, that intracellular killing even of C-resistant bacteria is increased following opsonization by C, but not by IgG. The mechanism of this C activity is yet unknown. C activation could lead either to an increased ingestion or increased discharge of lysosomal enzymes into the phagosome. The contribution of C activation to ingestion, killing and destruction of E. coli and to the secretion of lysosomal enzymes into the phagosome was therefore the subject of this investigation. To a monolayer of human PMN radiolabelled E. coli were added following opsonization with IgG, C or IgG and C. After various time intervals, cells and nonattached bacteria were separated, cells were destroyed and the cell sap was separated by centrifugation into three fractions: 1) membrane (and nuclei), 2) granula, and 3) cytoplasma.

Role of the Leukocyte and Chemical Mediators of the Acute Gouty Attack

Abstract: Experimental work in vivo (McCarty, 1970) has shown that the introduction of monosodium urate crystals into a joint cavity initiates an acute inflammatory response. Polymorphonuclear leukocytes are normally present in synovial fluid and phagocytosis of crystals by polymorphonuclear leukocytes occurs readily. Experimental work on animals has shown that the phagocytosis of crystals by polymorphonuclear leukocytes occurs independently of complement (Spilberg and Osterland, 1970). The crystals are taken into phagosomes which then merge with primary lysosomes to form phagolysosomes or secondary lysosomes. Electron microscopic studies indicate that after a crystal lies in contact with the membrane of the phagolysosome, dissolution of the membrane occurs and is followed by cell death (Schumacher and Phelps, 1968). Cell death, however, appears to be a slow process, since neutrophils which have previously ingested urate crystals in vitro have been reported to exhibit a normal phagocytic capacity for yeast (Turner et al., 1973). Weissmann and Rita (1972) have postulated that lysis of the lysosomal membrane is due to the interaction of weakly anionic urate crystals with the membrane, forming cooperative hydrogen bonds with phosphate esters of membrane phospholipids. Not only do urate crystals disrupt lysosomal membranes, they also lyse red cells (Wallingford and McCarty, 1971), the plasma membrane of polymorphonuclear leukocytes (Spilberg et al., 1975), and liposomes (Weissman and Rita, 1972), lamellar arrays of phospholipids containing cholesterol in their membranes.