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Biomedical subjects

M Baggiolini

Publications and source records attributed to M Baggiolini.

At least 235 records · Page 13Linked to original sources
PubMed1979

Subcellular localization of the superoxide-forming enzyme in human neutrophils.

The subcellular distribution of the superoxide (O2-)-forming enzyme in human neutrophils was investigated. Cells were activated by phorbolmyristate acetate or by opsonized zymosan, and were then fractionated by zonal-rate sedimentation at two different speeds. At high speed, the specific granules were resolved from the azurophils and the membrane fraction, while at low speed, the azurophil granules could be separated from fast-sedimenting particle aggregates. Under both conditions, the major portion of the O-2--forming activity (60--70% of the total) was found to be associated with the membrane fraction which was characterized by the presence of alkaline phosphatase, alkaline phosphodiesterase I, and acid aryl phosphatase. No significant O-2--forming activity was found in either specific or azurophil granules. Some activity was present in the fastest sedimenting fractions which, as shown by electron microscopy, were heterogeneous and contained aggregated material which included membrane fragments. These fractionation results provide strong additional support for the current view that the activable O-2--forming system is localized in the plasma membrane of human neutrophils.

Cell Fractionation↗
PubMed1979

[The release of proteinases from neutrophil leukocytes and macrophages].

The main source of proteinases that degrade tissue components in the course of inflammation are neutrophil leukocytes and macrophages. Both cells contain and/or produce a large variety of acid and neutral hydrolases including representatives of all four classes of tissue proteinases. Neutrophils are short-lived end cells with large enzyme stores (i.e. azurophil and specific granules) which they normally discharge in the course of phagocytosis. Macrophages are long-lived cells with a great potential for functional differentiation. In macrophages, proteinases and other lytic enzymes are released both by phagocytosis and by secretion (the latter particularly in activated macrophages) and replaced continuously by de novo synthesis. The acid and neutral proteinases of neutrophils and macrophages, their subcellular localization, their properties in relation to tissue damage and the mechanisms of their release are described.

Endopeptidases↗
PubMed1978

Role of phagocytosis in the activation of macrophages.

Macrophages were obtained by peritoneal lavage from untreated mice or from mice which had received either Brewer's thioglycollate broth or a suspension of streptococcus A cell walls intraperitoneally 4 days before. 3 h after harvesting, adherent cells from untreated mice were allowed to phagocytose zymosan, formaldehyde-treated sheep erythrocytes, or latex beads. Phagocytosis was stopped after 1 h and culture was continued for up to 10 days. Phagocytosis of zymosan or sheep erythrocytes triggered the immediate release of lysosomal glycosidases, stimulated the synthesis of cellular lactate dehydrogenase, and induced the delayed production and secretion of plasminogen activator . No such changes were observed upon phagocytosis of latex. Although all three particles used were phagocytosed, only zymosan and sheep erythrocytes stimulated glucose oxidation via the hexose monophosphate shunt. Similar findings were obtained in macrophages elicited with streptococcus A cell walls after zymosan phagocytosis. Thioglycollate-elicited macrophages, however, which were already secreting lysosomal hydrolases and plasminogen activator, could not be activated further by zymosan. The results of this study show that macrophages become activated after phagocytosis of particles that stimulate the activity of their hexose monophosphate shunt. The triggering event appears to be the burst of shunt activity itself or shunt-related biochemical reactions rather than phagocytic uptake per se or particle-dependent complement activation by the alternative pathway. Once initiated, macrophage activation proceeds independently of the intracellular fate of the ingested material .

Acetylglucosaminidase↗
PubMed1978

Secretion of lysosomal hydrolases by stimulated and nonstimulated macrophages.

Peritoneal macrophages were obtained from untreated mice and from mice treated with thioglycollate medium (TA), proteose peptone medium (PP), or a suspension of streptococcus A cell wall material (SA). The biochemical and secretory properties of these cells in long term cultures (up to 2 wk) were compared. TA-elicited macrophages contained more protein, lactate dehydrogenase, lysosomal hydrolases, and in particular, more plasminogen activator than the other cells studied. All types of macrophages studied were found to release considerable amounts of lysosomal hydrolases (beta-glucuronidase, N-acetyl-beta-glucosaminidase, alpha-mannosidase, and acid phosphatase) into the medium. Release was independent of phagocytosis and must, therefore, be regarded as true secretion. In both elicited and nonelicited macrophages, the rates of lysosomal enzyme secretion were virtually identical in the presence and in the absence of serum, and they were not enhanced by increasing serum concentrations. Lysosomal enzyme secretion in macrophages appears to depend on protein synthesis, since it was blocked by low concentrations of cycloheximide which neither affected cell viability nor lowered the intracellular enzyme levels. The amounts of lysosomal hydrolases secreted were highest in TA-elicited macrophages. The rates of secretion of PP- or SA-elicited and of nonelicited macrophages were about one-fourth of that of the TA-elicited cells. This difference, although significant, is much smaller than that observed for the secretion of plasminogen activator which was 20-50 times higher in TA-elicited cells. Acid glycosidases were also found in the peritoneal lavage media used for cell harvesting from both treated and nontreated mice. This indicates that active secretion of lysosomal hydrolases may be an in vivo property of the macrophage.

Animals↗
PubMed1978

The polymorphonuclear leukocyte.

Polymorphonuclear leukocytes (PMNs) are one of the main sources of enzymes responsible for tissue damage in inflammatory processes. These enzymes are stored in two types of cytoplasmic granules. Azurophil granules contain lysosomal hydrolases, neutral serine proteinases, and bactericidal elements (myeloperoxidase and lysozyme). Specific granules contain collagenase, lysozyme and lactoferrin but lack lysosomal hydrolases. PMNs store all four classes of tissue proteinases, carboxyl, thiol and serine proteinases in the azurophil granules, and metallo proteinases in the specific granules. Three serine proteinases have been identified, elastase, cathepsin G and a third enzyme, which together account for a large proportion of the protein of the azurophil granules. In the course of phagocytic events, all these enzymes are released extracellularly. The neutral proteinases degrade proteoglycans and collagen. In vitro, they stimulate B-lymphocytes, which suggests that they may have immuno-potentiating activity when they are released at sites of chronic inflammation.

Animals↗
PubMed1978

A volume adapter for use in a B-XIV zonal rotor.

A simple adapter for reducing the chamber volume of B-XIV-type rotors is described. The adapter consists of a disk-like body, which occupies the lower part of the rotor chamber, and an aluminum sleeve with four septa. The modified rotor has a volume of 272 ml and has proved very suitable for rate-sedimentation analysis of small amounts of biological material. The modified rotor is operated as is a standard B-XIV rotor.

Animals↗
PubMed1978

Capping of ricin-binding sites does not influence phagocytosis in human polymorphonuclear leukocytes.

Human polymorphonuclear leukocytes (PMN'S) were incubated at 0 degrees C with ferritin-conjugated ricin and warmed to 37 degrees C to induce capping of the ricin-binding sites. The PMNs were then allowed to phagocytose yeast or Staphylococcus epidermidis for 15 min, and processed for electron microscopy. Phagocytic uptake, granule fusion, and the fate of lectin-bound membrane were quantified by morphometry. Ricin-capped PMNs phagocytosed as extensively as untreated PMNs. Particles were ingested almost exclusively with a lectin-free portion of the plasmalemma. Fusion of granules with phagocytic vacuoles was not affected by ricin-induced capping. This indicates that ricin-binding sites are not involved in particle recognition and uptake.

Binding Sites↗
PubMed1978

Freeze-fracture of membrane fusions in phagocytosing polymorphonuclear leukocytes.

Freeze-fracture of rabbit polymorphonuclear leukocytes in the process of phagocytosing yeast cells shows changes in storage granule and phagosome membranes essentially similar to those described in mammalian secretroy cells during exocytosis. These changes consist of the clearing of intramembrane particle from limited zones of the fusing granule and phagosome membranes. After the completion of fusion, which leads to the incorporation of storage granule membrane into the phagosome membrane, particle-free patches are no longer visible, but the phagosome membrane contains some loose aggregates of particles. These data suggest that intracellular membrane fusion in polymorphonuclear leukocytes occurs through interaction of protein-depleted areas of the involved membranes.

Animals↗
PubMed1977

Collagenase is a component of the specific granules of human neutrophil leucocytes.

Azurophil and specific granules were isolated from human polymorphonuclear neutrophil leucocytes. Collagenase was almost exclusively a component of the specific granules. This finding is in contrast with the distribution of other proteolytic enzymes, which are localized in the azurophil (or lysosomal) granules.

Electrophoresis, Polyacrylamide Gel↗
PubMed1976

Capping of concanavalin A- or ricin-binding sites does not influence phagocytosis in polymorphonuclear leukocytes.

Rabbit polymorphonuclear leukocytes (PMNs) were capped with territin-conjugated concanavalin A or ricin, and then allowed to phagocytose yeast cells. Phagocytic activity and lectin distribution were determined by ultrastructural morphometry. Capped PMNs were found to phagocytose as efficiently as control PMNs, and always to ingest the particles with a lectin-free portion of their plasma membrane. This clearly indicates that concanavalin A- and ricin-binding sites of the PMN membrane are not involved in the recognition and phagocytosis of yeast particles.

Animals↗
PubMed1976

Ricin- and concanavalin A-binding sites on the surface of polymorphonuclear leukocytes have no receptor function in phagocytosis.

Human and rabbit polymorphonuclear leukocytes (PMN) were incubated at 0 degrees C with ferritin conjugates of ricin or concanavalin A,and subsequently brought to 37 degrees C in order to induce the formation of lectin caps. The PMN were then alllowed to phagocytose yeast cells or staphylococci for 15 min and were subsequently processed for electron microscopy. The micrographs were evaluated by morphometry. It was found that lectin-treated PMN phagocytose as efficiently as untreated cells. Capped cells always engulfed the particles with a lectin-free portion of their plasma membrane. This indicates that ricin- and concanavalin A-binding sites on the PMN surface are not involved in particle recognition and uptake. The virtual absence of lectin on the membrane of the phagocytic vacuoles suggests that capped PMN is functionally polarized and only able to phagocytose at the pole opposite the cap.

Animals↗
PubMed1976

In vitro stimulation of lymphocytes by neutral proteinases from human polymorphonuclear leukocyte granules.

Two neutral proteinases, polymorphonuclear leukocyte (PMN) elastase and cathepsin G, were purified from azurophil granules of human PMN. Both enzymes were found to stimulate both human and mouse lymphocytes in vitro. Experiments with mouse cells showed that the PMN proteinases are B-cell stimulants. Stimulation appears to depend on direct proteolytic action on the lymphocyte surface and not to require the mediation of serum factors of the help of T-cells.

Animals↗
PubMed1976

In vitro stimulation of lymphocytes by neutral proteinases from human polymorphonuclear leukocyte granules.

Two neutral proteinases from human polymorphonuclear leukocytes (PMN), an elastase and the chymotrypsin-like cathepsin G, were purified, and their actions on lymphocytes in culture were studied. Both PMN proteinases stimulate lymphocytes from human peripheral blood and from mouse spleen in vitro, but do not affect thymic cells from either normal or hydrocortisone-treated mice. In stimulated mouse spleen cell cultures, most of the developing blast cells bear surface immunoglobulins, and subsequently appear to engage in antibody synthesis. In their stimulatory action, the two PMN proteinases thus resemble the classic B-cell mitogen LPS and neutral pancreatic proteinases such as trypsin, chymotrypsin, and elastase. The effects of proteinase inhibitors indicate that lymphocyte stimulation is dependent on the proteolytic activity of the enzymes. This work suggests that PMN proteinases, which are released at sites of inflammation, may modulate the function of lymphocytes.

Animals↗