The localization by electron microscopy of nucleoside phosphatase activity in guinea pig phagocytic cells

Antigen-presenting cells, including Langerhans cells, veiled cells and interdigitating cells

The accessory functions attributed to macrophages, such as antigen presentation, are probably carried out by specialized, marrow-derived cells which always have Ia antigen on their surfaces. These cells are not actively phagocytic, but are mainly engaged in engulfing large volumes on fluid. They are found in the epidermis as sessile cells, the Langerhans cells, but some re-enter the dermis and appear in afferent lymph as actively moving, veiled cells. Here they are joined by other veiled cells which have differentiated in the dermis: both populations then enter the draining lymph node. A similar process of differentiation probably occurs in other specialized tissues leading to the formation of cells that enter the afferent lymph and become veiled cells. In the lymph node, veiled cells localize in the paracortex or T-dependent area and later differentiate into another sessile cell type, the interdigitating cell. The life-style of this family of cells appears to be well-adapted for the transport of antigen into the paracortex, an area from which free antigen is largely excluded, and it seems likely that T-cell activation is triggered by the arrival of veiled cells bearing a new antigen on their surfaces.

Quantification of reactive oxygen species generated by alveolar macrophages using lucigenin-enhanced chemiluminescence--methodical aspects

Alveolar macrophages lavaged from bovine lungs using Ca2(+)- and Mg2(+)-deprived saline containing EGTA for calcium chelation were cultivated in RPMI-1640 medium. The generation of reactive oxygen species (ROS) was assessed by determination of lucigenin-enhanced chemiluminescence (LUC-CL) using a LB 9505 C Biolumat. Monitoring of LUC-CL depends on various methodical parameters: besides medium constituents, the method of cell harvesting and the time-schedule of the protocol appear to be essential parameters that influence ROS-generation. In addition, the cell number (cell density) as well as the ratio of cell number to particle mass influence the amount of ROS-generation. Following exposure of cells to micronized quartz, we observed a dose-related increase in the generation of ROS.

Morphological changes and depressed phagocytic efficiency in Dictyostelium amoebae treated with toxic concentrations of cadmium

The morphology and phagocytic efficiency of Dictyostelium discoideum amoebae exposed to cadmium was investigated at two Cd concentrations: a low toxic concentration--7 X 10(-5) M, and a high toxic concentration--2 X 10(-4) M. Both concentrations inhibited growth completely; however, only in the culture containing a high toxic concentration of cadmium were severe ultrastructural anomalies observed, notably, nucleolar changes and autophagic vacuolar formation. Using biological indices we conclude that the high concentration of cadmium was lethal and that morphological changes associated with this dose of cadmium may be secondary to cell death. In contrast, amoebae treated with a low toxic but nonlethal concentration of Cd showed an altered size distribution of cytoplasmic vacuoles and a decreased phagocytic efficiency. Cultures whose growth was completely inhibited with cobalt were also examined, as were untreated control cultures. By 24 hr Cd-treated amoebae showed a 20% decrease in the cytoplasmic mean-vacuolar diameter and a 69% decrease in phagocytic efficiency whereas Co and untreated controls showed no significant decrease in the cytoplasmic mean-vacuolar diameter. Phagocytic efficiency was only slightly diminished by Co. Changes in vacuolar profiles had been shown earlier to be related to membrane utilization in Dictyostelium amoebae. Cd at low toxic concentrations affects membrane function in Dictyostelium amoebae.

Effect of 2450 MHz microwave energy on the blood-brain barrier to hydrophilic molecules. D. Brain temperature and blood-brain barrier permeability to hydrophilic tracers

Measurement of temperature within the cerebral cortex, hypothalamus, cerebellum and medulla of rats sham-, heat- or microwave-exposed revealed the presence of a thermal gradient within the brain. In all groups, cerebral cortex and the cerebellum were cooler than the deeper hypothalamus and medulla. Exposure to 2450 MHz CW microwaves or ambient heat (42 +/- 2 degrees C) resulted in measurable elevation of regional brain temperature, but without alteration of temperature gradients normally observed within the brain. Exposure to 20 mW/cm2 (SAR approximately equal to 4 W/kg) for 30, 90 or 180 min induced a small, but significantly (U = 0, P less than 0.05) increased temperature of the colon, and in each region of the brain studied. Exposure to an incident power density of 65 mW/cm2 (SAR approximately equal to 13.0 W/kg) for 30 or 90 min or to ambient heat (42 +/- 2 degrees C) for 90 min resulted in a substantially greater thermal response as indicated by higher colonic and brain temperatures. Comparison of regional brain temperature with individual colonic temperatures is expressed as delta T = t degrees Cbrain--t degrees Ccolon. In general delta T values for ambient heat or microwave-exposed rats did not differ significantly from those of sham-exposed animals. Exposure to microwaves or ambient heat did not alter the general relationships between regional brain and colonic temperatures, i.e., cortical and cerebellar temperatures were always below and hypothalamic and medullary temperatures always above corresponding colonic temperatures. The plotted temperature data (brain vs colonic temperature) indicate a linear relationship between brain and colonic temperatures. Levels of sodium fluorescein (NAFl), horseradish peroxidase (HRP) and [14C]sucrose (described in preceding papers) within the brain show a high correlation (P less than 0.05) with brain temperature. Suppression of blood-brain barrier permeability to hydrophilic tracers was most pronounced at brain temperatures exceeding approximately 40 degrees C and is demonstrated to be temperature dependent.

Cytochemical study of liposome and lipid vesicle phagocytosis

Electron microscopy cytochemistry has been used to study the cytoplasmic location of liposomes and lipid vesicles following specific antibody-dependent phagocytosis. The vesicle compositions were 94-99 mol% 'fluid' lipid (egg phosphatidylcholine or dimyristoylphosphatidylcholine at 37 degrees C or 'solid' lipid (dipalmitoylphosphatidylcholine at 37 degrees C). In some cases, 4 mol% phosphatidylserine was included in the vesicle membrane so as to vary the surface charge density. These vesicles undergo specific antibody-dependent phagocytosis by RAW264 macrophages when the lipid membranes contain 1-2 mol% dinitrophenyl lipid hapten in the presence of rabbit anti-dinitrophenyl IgG antibody. Internalized lipid vesicles can be visualized with the electron microscope when ferritin is trapped in the internal aqueous compartments prior to internalization. The lipid vesicles were demonstrated to be internal to the macrophage plasma membranes by selectively staining the plasma membranes with Ruthenium red. The cytoplasmic location of vesicles and liposomes was studied by electron microscopic staining for activities of the following enzymes: (1) acid phosphatase; (2) inorganic trimetaphosphatase; (3) adenosine triphosphatase; and (4) glucose-6-phosphatase. The first two enzymatic activities were found in association with ferritin-containing vesicles after antibody-dependent phagocytosis, showing the formation of vesicle-containing phagolysosomes. Adenosine triphosphatase and glucose-6-phosphatase were primary not associated with the vesicles, suggesting a minimal association of vesicles with plasma membrane, Golgi, endoplasmic reticulum and perinuclear cisternae. Phagosome-lysosome fusion did not appear to depend on the type of target lipid vesicle or liposome, on the 'fluidity' of the target membrane, or the presence of phosphatidylserine in the target membrane.

The influence of some metabolic inhibitors on phagocytic activity of mouse macrophages in vitro

The action of different metabolic inhibitors on phagocytosis by macrophages from mouse peritoneal exudate cultured in vitro was studied. The following metabolic inhibitors were tested: sodium iodoacetate, sodium fluoride, sodium fluoroacetate, sodium malonate, 2-4-dinitrophenol, sodium azide, ouabain and cycloheximide, all at the concentration of 10(-3) M. Iodoacetate caused a strong inhibitory effect on phagocytosis; this observation confirms that glycolysis is the main source of energy for the phagocytic process. On the contrary, fluoride, although it is an effective inhibitor of glycolysis, did not exert any effect. This difference may be explained by the fact that sodium fluoride blocks anaerobic glycolysis only in vitro at an unphysiological temperature (0 degrees C). Fluoroacetate and malonate, two compounds which interfere with the Krebs cycle, did not inhibit phagocytosis, but it is known that the Krebs cycle activity is poorly developed in the macrophagic cells. Sodium azide and 2-4-dinitrophenol, two inhibitors of oxidative phosphorylation, showed an effect on phagocytosis only after 3 h of contact with the cell cultures. Ouabain blocks Na+ and K+ transport across the plasma membrane and, probably, it inhibited phagocytosis by interfering with the movements of the cell membrane. Finally, the mode of action of cycloheximide on phagocytosis is uncertain. This compound inhibits the protein synthesis and, perhaps, it can act by preventing the renewal of the cell membrane.

Differences in surface membrane ecto-ATPase and ecto-AMPase in normal and malignant cells. I. Decrease in ecto-ATPase in myeloid leukemic cells and the independent regulation of ecto-ATPase and ecto-AMPase

The hydrolysis of ATP and AMP by enzymes located on the external side of the plasma membrane (ecto-ATPase and ecto-AMPase) was studied in mouse myeloid leukemic cells, normal early myeloid cells, and normal mature granulocytes and macrophages. Nine clones of myeloid leukemic cells were used belonging to three groups that differ in their ability to be induced to differentiate by the differentiation-inducing protein MGI. These three groups consisted of MGI+D+ that can be induced to undergo complete differentiation, MGI+D- that can be induced to partially differentiate and MGI-D- with no induction of differentiation. The ecto-ATPase activity of normal early myeloid cells was similar to that of normal mature granulocytes and macrophages and higher than that of any of the leukemic cells. Among the leukemic cells, the MGI-D- cells had the highest level of ecto-ATPase activity. The behaviour of ecto-AMPase differed from that of ecto-ATPase. Some MGI-D- clones had a higher ecto-AMPase activity than normal cells and MGI+D- and MGI+D+ cells showed no detectable activity. Neither the ecto-ATP-ase nor ecto-AMPase activities changed after induction of differentiation in normal early myeloid or MGI+D+ leukemic cells. The results indicate that the myeloid leukemic cells had a decreased ability to hydrolyse external ATP, that there can be an independent regulation of ecto-ATPase and ecto-AMPase and that neither of these enzyme activities changed during differentiation.

The influence of some metabolic inhibitors on in vitro phagocytizing macrophages. I. The behaviour of human macrophages

In the present work the uptake of foreign materials by macrophages has been studied in order to elucidate its possible energy-dependent mechanisms. We used monolayer cultures of macrophages from human peripheral venous blood, treated with the following metabolic inhibitors: iodoacetic acid, fluoroacetic acid, sodium fluoride, sodium malonate, sodium azide, 2-4-dinitrophenol, cycloheximide, and ouabain. The test assay was performed by using a zymosan particles suspension in Mc Coy 5 A medium supplemented as follows. The quantitation of phagocytosis was obtained by direct count of intracellular zymosan particles by oil 100X microscopy and the results were submitted to a statistical evaluation. The most effective inhibitor we found was iodoacetate, an inhibitor of anaerobic glycolysis, but fluoride, which acts on the same metabolic pathway at a different site, was quite ineffective. The same ineffectiveness we found for fluoracetate and malonate which act on the Krebs cycle. On the contrary, dinitrophenol (uncoupler of oxidative phosphorylation), azide (inhibitor of cytochrome linked-phosphorylation), ouabain (inhibitor of membrane ATPase activity) and cycloheximide (inhibitor of protein synthesis) give a remarkable decrease of index of phagocytosis after a 3h incubation. In conclusion, we can suppose that the energy-dependent phagocytosis is first depending on transport across the cell membrane (ATPase activity and protein synthesis) and second both on anaerobic glycolysis and oxidative phosphorylation.

[On the endogenous peroxidase in the spleen of swine (author's transl)]

We studied the distribution of endogenous peroxidase in the spleen of swine by modifications of the Graham and Karnovsky diaminobenzidine procedure. There is a peroxidatic activity in the majority of the ellipsoid cells (cells of the sheathed capillaries of Schweigger-Seidel), which is localized in the endoplasmic reticulum and the perinuclear cisterna. This staining is inhibited completely by aminotriazole and is rapidly destroyed even by low concentratoins of glutaraldehyde. Furthermore, the reaction is abolished after boiling of tissue sections or in the absence of H2O2. The macrophages of the red pulp and a minority of the ellipsoid cells are peroxidase negative. Our results are discussed in respect to some recent studies on the system of mononuclear phagocytes. It is suggested, that the enzyme active ellipsoid cells represent a special form of macrophages, enzyme histochemically related to Kupffer cells and resident peritoneal macrophages. The enzyme negative cells of the ellipsoids are probably fibroblasts.

Inhibition of Pseudomonas aeruginosa by hyperbaric oxygen: interaction with mouse peritoneal exudate cells

High-pressure oxygen (HPO) therapy for Pseudomonas aeruginosa infections of burn wounds has not been as effective as in vitro studies predicted. Mitigation of HPO toxicity for P. aeruginosa by nutrients present at the burn site could explain the lack of in vivo success. Alternatively, HPO-induced depression of host defense mechanisms could negate beneficial effects arising from HPOs known toxicity for P. aeruginosa. Accordingly, mouse peritoneal exudate cells (PEC), preincubated for 24 h in 1 atm of air-CO(2), were used to study the in vitro effects of HPO or air-CO(2) on phagocytosis of P. aeruginosa or sheep erythrocytes (SRBC). Subsequent 2-h exposures of PEC to increasing numbers of bacteria, in an air-CO(2) atmosphere, decreased the percentage of bacteria cleared as well as PEC viability. Similar exposures of PEC to bacteria in an HPO atmosphere prevented the loss of PEC viability and increased bacterial clearance. In control experiments, increasing the number of SRBC relative to PEC decreased the percentage of SRBC cleared without decreasing PEC viability, as determined under air-CO(2); short (2 h) exposure to HPO did not affect SRBC clearance. Microscopic examination of PEC indicated that a 24-h preincubation in HPO decreased the percentage of PEC which could ingest SRBC during subsequent experimental exposures (2 h) to air-CO(2) or HPO. These data suggest that short periods of exposure to HPO promote the ability of PEC to clear pseudomonads by adversely affecting the bacteria. This in turn prevents a pseudomonad-induced depression of PEC viability and function. In contrast, prolonged HPO exposure may be detrimental to phagocytic activity.

Mechanisms of pathogenesis in Listeria monocytogenes infection. V. Early imbalance in host energy metabolism during experimental listeriosis

Early changes in hepatic carbohydrate metabolism without apparent hepatocyte dysfunction were reported previously in mice infected with Listeria monocytogenes. This study was undertaken to examine possible imbalance in host regulatory mechanisms which might be responsible for these changes. Female CD-1 mice fasted 12 hr prior to the experiments were injected intraperitoneally with 10(5), 10(6), or 10(7)Listeria. Control mice received either 10(9) heat-killed Listeria or 150 mug of Salmonella typhimurium lipopolysaccharide. Hepatic glycogen, adenosine triphosphate (ATP), adenosine diphosphate (ADP), and nicotinamide adenine dinucleotide (NAD) (NAD(+), NADH, NADP(+), and NADPH) levels were assayed periodically. Activities of ATP hydrolyzing enzyme and NAD glycohydrolase were measured at various intervals after infection. Decreases in glycogen occurred as early as 10 hr after infection. Responses in the controls differed from those in infected mice. Hepatic ATP levels decreased as early as 10 hr after infection, with concomitant increases noted in ADP. Hepatic ATP hydrolyzing enzyme activity increased as the infection progressed. Decreases were noted in hepatic NAD levels, with the greatest reduction in the reduced form of NAD. Slight changes were observed after 10 hr, and greater differences were noted 20 hr after infection. The magnitude of these biochemical changes appeared to be dose-dependent. Significant increases in hepatic NAD glycohydrolase activity were noted as the infection progressed. Small but significant increases in serum inorganic phosphate were noted 10 and 20 hr after infection, with a larger increase observed 30 hr after infection. The results indicate impairment of host energy metabolism early in the course of experimental listeriosis.

Ultrastructure of Pseudomonas saccharophila at early and late log phase of growth

The fine structure of Pseudomonas saccharophila, a soil bacterium, is similar to that of the marine Pseudomonas reported by Wiebe and Chapman. The unit membrane of the plasma membrane is clearly seen in some areas of thin sections. The ribonucleoprotein granules are distributed in the cytoplasm of the cell. Cells of P. saccharophila during early exponential phase are large, and most of them contain a large number of poly-beta-hydroxybutyrate granules. Some of the granules are quite large and occupy up to three-fourths of the cross section of the cell. Thin sections of the cells in the late log phase, however, show fewer and smaller poly-beta-hydroxybutyrate granules located in the central region of the cell. Negative-stained and freeze-fracture preparations show that the outer surface of the cell wall of P. saccharophila is covered with a large number of tiny granules and long, slender flagella. The outer surface of the plasma membrane appears to be smoother than the outer surface of the cell wall, and it also contains numerous granules. Since the outer surface of the cell wall is quite smooth in freeze-fracture preparations, the wrinkled appearance in thin sections is probably an artifact of fixation and dehydration. The poly-beta-hydroxybutyrate did not solidify at the freezing temperature used (approximately -150 C), and it was consequently pulled out in a spikelike structure during the fracturing process. P. saccharophila, under the conditions in our study, appears to multiply by the constrictive type of cell division.

The preparation and properties of macrophage-L cell hybrids

The plasma membrane of the mouse peritoneal macrophage has specific receptors which enable the cell to bind IgG or complement-coated sheep red cells and is also rich in a divalent cation-dependent adenosine triphosphatase (ATPase) activity. L cells lack these macrophage membrane markers. The question of macrophage membrane receptor expression was investigated in DBA/2 mouse macrophage x mouse LMTK(-) cell hybrids produced with the aid of Sendai virus. Three independent clones and one mass culture were isolated by their ability to grow in hypoxanthine, aminopterin, and thymidine (HAT) selection medium. These hybrids retained 85-100% of the sum of two parent cells' chromosomes and expressed several genes derived from both parents, including glucose phosphate isomerase isozymes and H-2 antigens. The hybrids displayed ATPase activity which was intermediate between that of the macrophage and L cell. The macrophage specific receptors for antibody or complement-coated red cells could not be demonstrated on hybrid cells. The selective absence of these receptors is probably because of a failure in gene expression rather than to loss of genes.

Macrophage-melanoma cell heterokaryons. IV. Unmasking the macrophage-specific membrane receptor

Mouse peritoneal macrophages possess a specific plasma membrane receptor for antibody-coated particles. Sheep red cells coated with rabbit 7S antibody attach readily to the macrophage surface and are subsequently interiorized. The fusion of macrophage with nonphagocytic mouse melanoma cells produces heterokaryons in which the macrophage receptor is drastically altered. The receptor is present shortly after fusion and heterokaryons are actively phagocytic. The ability to bind and ingest red cells is, however, progressively lost over the next 12-24 hr and does not reappear thereafter. Exposure of heterokaryons to trypsin (1-100 microg/ml for 30 min at 37 degrees C) results in the reappearance of initial receptor activity and the unmasking of the surface receptor. This property is again lost upon subsequent cultivation. The masking process takes place when cells are cultivated in the absence of IgG so that the adsorption of antibody from the medium is not responsible for this phenomenon. Inhibition of heterokaryon protein synthesis preserves phagocytic activity in a reversible fashion and prevents the masking of macrophage receptors. Inhibition of melanoma RNA synthesis before fusion is also able to block subsequent masking, but is ineffective if delayed until after fusion. Ultraviolet irradiation of the melanoma cell before fusion prevents subsequent masking, whereas similar treatment of the macrophage has no effect. Cells differ markedly in their ability to mask the macrophage phagocytic receptor after fusion. Ehrlich ascites tumor cells mask the receptor rapidly, primary chick fibroblasts minimally, and embryonic chick erythrocytes not at all.

Macrophage-melanocyte heterokaryons. I. Preparation and properties

High yields of mouse macrophage-melanocyte heterokaryons and macrophage-macrophage homokaryons were obtained through the virus-induced fusion of cells spread on a glass surface. After fusion there was a striking reorganization of cellular architecture by means of a colcemid-sensitive process. Heterokaryons were isolated through the use of differential trypsinization and many underwent division to form melanocyte-like hybrids. The selective uptake of dextran sulfate by macrophages served as a useful cytoplasmic marker in identifying hybrids. Many characteristic macrophage properties were altered in the heterokaryons. Within an hour of fusion macrophage nuclei became swollen, nucleoli were more prominent, and increased nuclear RNA synthesis occurred. 3 hr after fusion, a wave of DNA synthesis took place in the previously dormant macrophage nuclei. The fate of typical macrophage markers was examined in both heterokaryons and homokaryons. Macrophage homokaryons continued to exhibit active phagocytosis of sensitized erythrocytes, whereas this capacity was lost irreversibly in heterokaryons. The loss of phagocytic activity of heterokaryons occurred at an exponential rate and was accelerated by high concentrations of calf serum. Another macrophage surface marker, a divalent cation-dependent adenosine triphosphatase (ATPase), could be demonstrated histochemically on heterokaryons. Shortly after fusion, it was present in discrete regions, but it became more diffuse and disappeared within a day. Acid phosphatase-positive secondary lysosomes and retractile lipid droplets disappeared from heterokaryons but continued to accumulate in macrophage homokaryons. These observations indicate that typical macrophage properties cease to be expressed in heterokaryons, and melanocyte functions presumably predominate in heterokaryons and hybrids.